Soft tissue measurement and balancing systems and methods

ABSTRACT

Systems and methods for joint replacement are provided. The systems and methods can include a surgical orientation device and/or a reference sensor device. The surgical orientation device and orthopedic fixtures can be used to locate the orientation of an axis in the body, to adjust an orientation of a cutting plane or planes along a bony surface, to distract a joint, to measure an angle, to orient a cutting guide, to orient a resection guide, to resect the femur, or to otherwise assist in an orthopedic procedure or procedures.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/920,202, filed Mar. 13, 2018, which claims benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62/471,177, filed Mar.14, 2017, each of which is incorporated in its entirety by referenceherein. Any and all applications for which a foreign or domesticpriority claim is identified in the Application Data Sheet as filed withthe present application is hereby incorporated by reference in itsentirety under 37 CFR 1.57.

BACKGROUND Field

This application is directed to the field of joint replacement, andparticularly to surgical tools and methods for soft tissue balancing.

Description of the Related Art

Joint replacement procedures, including knee joint replacementprocedures, are commonly used to replace a patient's joint with aprosthetic joint component or components. Such procedures often use asystem or systems of surgical tools and devices, including, but notlimited to, cutting guides (e.g. cutting blocks) and surgical guides, tomake surgical cuts along a portion or portions of the patient's bone.

Current systems and methods often use expensive, complex, bulky, and/ormassive computer navigation systems which require a computer orcomputers, as well as three dimensional imaging, to track a spatiallocation and/or movement of a surgical instrument or landmark in thehuman body. These systems are used generally to assist a user todetermine where in space a tool or landmark is located, and oftenrequire extensive training, cost, and space.

Where such complex and costly system are not used, simple methods areused, such “eyeballing” the alignment of rods with anatomical features,such as leg bones. These simple methods are not sufficiently accurate toreliably align and place implant components and the bones to which suchcomponents are attached. Without accurate, reliable placement suboptimaloutcomes can result, such as with poor tissue balancing.

SUMMARY

Accordingly, there is a lack of devices, systems and methods that can beused to provide balancing, such as gap balancing and soft tissuebalancing during Total Knee Arthroplasty (TKA). There is a need forbalancing and alignment systems that can be integrated together toprovide both measured resection and balancing. Described herein aredevices, system and methods to guide one or more cuts.

In some embodiments, an orthopedic system for orienting a cutting planeduring a joint replacement procedure is provided. The system can includea tibial baseplate. The system can include a femoral baseplate. Thesystem can include a surgical orientation device coupled or configuredto couple to the at least one of the tibial baseplate and the femoralbaseplate. The surgical orientation device can include a housing. Thesurgical orientation device can include an inertial sensor configured tomonitor the orientation of the surgical orientation device in athree-dimensional coordinate reference system while distracting thejoint. The inertial sensor can be disposed on or in the housing. Thesurgical orientation device can include a user interface comprising adisplay screen configured to display a measurement related todistracting the joint.

In some embodiments, the inertial sensor comprises at least onegyroscopic sensor, accelerometer sensor, tilt sensor, and/or othersimilar device or devices configured to measure, and/or facilitatedetermination of, an orientation of the surgical orientation device. Insome embodiments, the inertial sensor can be configured to providemeasurements relative to a reference point, line, plane, and/orgravitational zero. In some embodiments, the inertial sensor comprisesgyroscopic sensors configured to detect angular position changes oraccelerometers configured to detect linear position changes. The systemcan include a drill guide coupled with the tibial baseplate. The systemcan include a reference sensor device comprising a camera. In someembodiments, the camera is oriented transverse to a longitudinal axis ofa housing of the reference sensor device. In some embodiments, thecamera is configured to capture an image of a linear scale or otherwisemake or confirm the measurement related to the distracting the kneejoint.

In some embodiments, an orthopedic orientation system for use in a jointprocedure is provided. The system can include a tibial baseplate. Thesystem can include a femoral baseplate. The system can include anadjustment device enabling at least one degree of freedom of the femoralbaseplate relative to the tibial baseplate when the tibial baseplate isin a fixed position and orientation relative to the tibia. The systemcan include the adjustment device enabling at least one additional anddifferent degree of freedom of the femoral baseplate relative to thetibial baseplate when the tibial baseplate is in a fixed position andorientation relative to the tibia. The system can include a firstorientation device configured to be coupled to the femoral baseplate.The first orientation device can include a sensor located within thehousing, the sensor configured to monitor the position and/ororientation of the first orientation device. The first orientationdevice can include a display configured to inform a user of the positionand/or orientation of the first orientation device. The system caninclude a second orientation device configured to be coupled to thetibial baseplate.

In some embodiments, the sensor comprises gyroscopic sensors to detectangular position changes and/or accelerometers to detect linear positionchanges. The sensor can alternatively or additionally includegravitational, magnetic, and/or other inertial sensors in otherembodiments. In some embodiments, the system is configured to determinethe orientation of the mechanical axis of the joint. In someembodiments, the at least one degree of freedom of the femoral baseplaterelative to the tibial baseplate includes or is translation. In someembodiments, the at least one additional degree of freedom of thefemoral baseplate relative to the tibial baseplate includes or isrotation.

In some embodiments, a method of performing an orthopedic procedure isprovided. The method can include coupling a first orientation devicewith a portion of the knee joint, the surgical orientation devicecomprising a first inertial sensor. The method can include coupling asecond orientation device with a portion of the knee joint, the secondsurgical orientation device comprising a second inertial sensor. Themethod can include collecting an inertial sensor output from the firstinertial sensor or the second inertial sensor. The method can includedistracting the knee joint. The method can include cutting the femur.The method can include determining with the first orientation device andthe first orientation device a location of the mechanical axis of a legor of a bone adjacent to the knee joint, e.g. the femur or the tibia.The method can include displaying the inertial sensor output from thefirst inertial sensor or the second inertial sensor. The method caninclude storing the inertial sensor output from the first inertialsensor or the second inertial sensor. The method can include comparingthe inertial sensor output at a first time and a second time during theprocedure. The method can include calculating, measuring, detectingand/or collecting a distraction distance. In some embodiments,collecting a distraction distance comprises capturing an image. In otherembodiments collecting includes a distraction distance. The method caninclude inserting one or more pins into the femur. The method caninclude mounting a cutting block to the one or more pins. The method caninclude coupling a drill guide to the knee joint.

In some embodiments, an orthopedic system for orienting a cutting planeduring a joint replacement procedure is provided. The system can includea tibial member configured to couple to tibia. The system can include aguide coupled to the tibial member, the guide configured to guide theinsertion of pins into a femur. The system can include a surgicalorientation device coupled or configured to couple to the at least oneof the tibia or the femur. The surgical orientation device can include ahousing. The surgical orientation device can include an inertial sensorconfigured to monitor the orientation of the surgical orientation devicein a three-dimensional coordinate reference system while distracting thejoint. The surgical orientation device can include a user interfacecomprising a display screen configured to display a measurement relatedto femur rotation.

In some embodiments, an orthopedic system for orienting a cutting planeduring a joint replacement procedure is provided. The system can includea tibial member. The system can include a femoral member. The system caninclude a surgical orientation device coupled or configured to couple tothe at least one of the tibial member and the femoral member. Thesurgical orientation device can include a housing. The surgicalorientation device can include an inertial sensor configured to monitorthe orientation of the surgical orientation device in athree-dimensional coordinate reference system while distracting thejoint. The surgical orientation device can include a user interfacecomprising a display screen configured to display a measurement relatedto distracting the joint.

The system can include a reference sensor device coupled or configuredto couple to the at least one of the tibial member and the femoralmember. In some embodiments, the surgical orientation device isconfigured to couple to the femoral member and the reference sensordevice is configured to couple to the tibial member. In someembodiments, the inertial sensor comprises at least one gyroscopicsensor, accelerometer sensor, tilt sensor, and/or other similar deviceor devices configured to measure, and/or facilitate determination of, anorientation of the surgical orientation device. In some embodiments, theinertial sensor can be configured to provide measurements relative to areference point, line, plane, and/or gravitational zero. In someembodiments, the inertial sensor comprises gyroscopic sensors configuredto detect angular position changes or accelerometers configured todetect linear position changes. The system can include a drill guidecoupled with the tibial member. The system can include a resection guidecoupled with the tibial member. The system can include a referencesensor device comprising a camera. In some embodiments, the camera isoriented transverse to a longitudinal axis of a housing of the referencesensor device. In some embodiments, the camera is configured to capturean image of the measurement related to the distracting the knee joint.In some embodiments, the measurement comprises a distance measurementcorresponding to a distance between the tibia and the femur. In someembodiments, the measurement is configured to correspond to ameasurement marking on a resection guide. In some embodiments, themeasurement comprises a distance measurement to match a gap inextension. In some embodiments, the measurement comprises a distancemeasurement to facilitate the posterior femoral cut. In someembodiments, the measurement comprises an angle measurementcorresponding to an angle between the tibia and the femur. In someembodiments, the measurement comprises an angle measurement tofacilitate soft tissue release. The system can include a moveableinterface to stabilize the orthopedic system against the tibia. In someembodiments, the moveable interface is configured to limit insertion ofthe tibial member in the joint space. The system can include a resectionguide.

In some embodiments, an orthopedic orientation system, for use in ajoint procedure, is provided. The system can include a tibial member.The system can include a femoral member. The system can include anadjustment device enabling at least one degree of freedom of the femoralmember relative to the tibial member when the tibial baseplate is in afixed position and orientation relative to the tibia. In someembodiments, the adjustment device enabling at least one additional anddifferent degree of freedom of the femoral member relative to the tibialmember when the tibial member is in a fixed position and orientationrelative to the tibia. The system can include a first orientation deviceconfigured to be coupled to the femoral baseplate. The first orientationdevice can include a sensor located within the housing, the sensorconfigured to monitor the position and/or orientation of the firstorientation device. The first orientation device can include a displayconfigured to inform a user of the position and/or orientation of thefirst orientation device. The system can include a second orientationdevice configured to be coupled to the tibial member.

In some embodiments, the sensor comprises gyroscopic sensors to detectangular position changes and/or accelerometers to detect linear positionchanges. In some embodiments, the system is configured to determine theorientation of the mechanical axis of the joint. In some embodiments,the at least one degree of freedom of the femoral member relative to thetibial member is translation. In some embodiments, the at least onedegree of freedom of the femoral member relative to the tibial memberrelates to distraction between the femur and the tibia. In someembodiments, the at least one additional degree of freedom of thefemoral member relative to the tibial member is rotation. In someembodiments, the adjustment device comprises a rounded portion of a postconfigured to move within a rounded guide portion. In some embodiments,the adjustment device comprises a rack and drive pinion. In someembodiments, the adjustment device comprises a pawl and ratchet. In someembodiments, the adjustment device is configured to apply a forcebetween 150 N and 200 N. In some embodiments, the adjustment devicecomprises a post comprising a portion with a round or circularcross-section. The system can include a bracket, wherein a longitudinalaxis of the first orientation device is offset from a longitudinal axisof the second orientation device when the first orientation device iscoupled with the bracket. The system can include a bracket whichpositions the first orientation device to the side of the secondorientation device. In some embodiments, the second orientation devicecomprises a camera configured to capture an image of a marking relatedto a distraction distance. In some embodiments, the second orientationdevice comprises a camera configured to capture an image of a portion ofa post of the adjustment device.

In some embodiments, a method of performing an orthopedic procedure isprovided. The method can include coupling a first orientation devicewith a portion of the knee joint, the surgical orientation devicecomprising a first inertial sensor. The method can include coupling asecond orientation device with a portion of the knee joint, the secondsurgical orientation device comprising a second inertial sensor. Themethod can include collecting an inertial sensor output from the firstinertial sensor or the second inertial sensor. The method can includedistracting the knee joint. The method can include cutting the femur.

The method can include determining with the first orientation device andthe second orientation device a location of the mechanical axis of abone adjacent to the knee joint. The method can include displaying theinertial sensor output from the first inertial sensor or the secondinertial sensor. The method can include storing the inertial sensoroutput from the first inertial sensor or the second inertial sensor. Themethod can include comparing the inertial sensor output at a first timeand a second time during the procedure. The method can includecollecting a distraction distance. In some embodiments, collecting adistraction distance comprises capturing an image. The method caninclude inserting one or more pins into the femur. The method caninclude mounting a cutting block to the one or more pins. The method caninclude coupling a drill guide to the knee joint.

In some embodiments, a method of performing an orthopedic procedure isprovided. The method can include coupling a first orientation devicewith at least one of a tibial member and a femoral member, the firstorientation device comprising a first inertial sensor. The method caninclude coupling a second orientation device with at least one of thetibial member and the femoral member. The method can include insertingthe tibial member and the femoral member in the joint space. The methodcan include distracting the knee joint. The method can include balancingthe soft tissue.

The method can include determining with the first orientation device andthe second orientation device a location of the mechanical axis of thelimb. The method can include displaying a distraction distance on adisplay of the first orientation device. The method can includedisplaying a femoral angle on a display of the first orientation device.

The method can include storing a distraction distance in a memory of thefirst orientation device. The method can include storing a femoral anglein a memory of the first orientation device. The method can includecomparing a distraction distance in extension and flexion. The methodcan include collecting a distraction distance. In some embodiments,collecting a distraction distance comprises capturing an image. In someembodiments, coupling a first orientation device with a portion of theknee joint comprises coupling the first orientation device to a femoralmember. In some embodiments, coupling a second orientation device with aportion of the knee joint comprises coupling the second orientationdevice to a tibial member. In some embodiments, distracting the kneejoint comprises distracting the knee joint in extension. The method caninclude recording an extension gap distance. The method can includedistracting the knee joint in flexion after recording an extension gapdistance. The method can include matching the extension gap distancewith a marking on a resection guide. The method can include performing aposterior femoral cut corresponding to the extension gap measurement. Insome embodiments, distracting the knee joint comprises distracting theknee joint in extension and balancing the soft tissue comprisesbalancing the soft tissue in extension. In some embodiments, balancingthe soft tissue comprises balancing the soft tissue only in extension.The method can include measuring a femoral rotation angle in extensionand flexion. The method can include recording a femoral rotation anglein flexion.

In some embodiments, an orthopedic system for orienting a cutting planeduring a joint replacement procedure is provided. The system can includea tibial member coupled to tibia. The system can include a guide coupledto the tibial member. The system can include a surgical orientationdevice coupled or configured to couple to the at least one of the tibiaor the femur. The surgical orientation device can include a housing. Thesurgical orientation device can include an inertial sensor configured tomonitor the orientation of the surgical orientation device in athree-dimensional coordinate reference system while distracting thejoint. The surgical orientation device can include a user interfacecomprising a display screen configured to display a measurement relatedto femur rotation.

In some embodiments, the guide is configured to guide the insertion ofpins into a femur. In some embodiments, the guide is configured to guidethe posterior femoral cut.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages are described belowwith reference to the drawings, which are intended to illustrate but notto limit the inventions. In the drawings, like reference charactersdenote corresponding features consistently throughout similarembodiments.

FIGS. 1A-1C illustrate an assembled view of a femoral preparationsystem.

FIGS. 2A-2C illustrate an assembled view of a tibial preparation system.

FIGS. 3A-3E illustrate views of a femoral preparation and kneedistraction system.

FIGS. 4A-4B illustrate views of a tibial system of the femoralpreparation and knee distraction system of FIG. 3A.

FIGS. 5A-5D illustrate views of an actuation system of the femoralpreparation and knee distraction system of FIG. 3A.

FIGS. 6A-6B illustrate views of a reference sensor device of the femoralpreparation and knee distraction system of FIG. 3A.

FIGS. 7A-7B illustrate views of a femoral system of the femoralpreparation and knee distraction system of FIG. 3A.

FIGS. 8A-8B illustrate views of a drill guide coupled with the femoralsystem of FIG. 7A-7B.

FIG. 9A illustrates the femoral preparation and knee distraction systemof FIG. 3A disposed in a joint space between a femur and a tibia, withthe femur and tibia placed in flexion.

FIG. 9B illustrates a subsystem of the femoral preparation and kneedistraction system of 9A including a reference device.

FIG. 9C illustrate a subsystem of the femoral preparation and kneedistraction system of 9A including the drill guide.

FIG. 10 is a view of another embodiment of a femoral preparation andknee distraction system.

FIGS. 11A-11F are views of a femoral preparation and knee distractionsystem for soft tissue balancing, illustrating one method of using thesystem.

FIGS. 12A-12E are views of a femoral preparation and knee distractionsystem for soft tissue balancing.

FIGS. 13A-13E illustrate views of another embodiment of a femoralpreparation and knee distraction system.

FIGS. 14A-14B illustrate views of a tibial system of the femoralpreparation and knee distraction system of FIG. 13A.

FIGS. 15A-15E illustrate views of an actuation system of the femoralpreparation and knee distraction system of FIG. 13A.

FIG. 16A illustrates a view of a moveable interface of the femoralpreparation and knee distraction system of FIG. 13A.

FIG. 16B illustrates a view of a moveable interface lock of the femoralpreparation and knee distraction system of FIG. 13A.

FIGS. 17A-17B illustrate views of a femoral system of the femoralpreparation and knee distraction system of FIG. 13A.

FIGS. 18A-18B illustrate views of a resection guide coupled with thefemoral system of FIG. 17A-17B.

FIG. 19A illustrates the femoral preparation and knee distraction systemof FIG. 13A disposed in a joint space of a schematic knee joint placedin flexion.

FIG. 19B illustrates a front view the femoral preparation and kneedistraction system of FIG. 13A disposed in a joint space of a schematicknee joint placed in flexion.

FIG. 19C illustrates a subsystem of the femoral preparation and kneedistraction system of FIG. 13A including the tibial system of FIGS.14A-14B.

FIG. 19D illustrate a subsystem of the femoral preparation and kneedistraction system of FIG. 13A including the tibial system of FIGS.14A-14B.

FIG. 19E illustrate a subsystem of the femoral preparation and kneedistraction system of FIG. 13A including the moveable interface.

FIG. 19F illustrate a subsystem of the femoral preparation and kneedistraction system of FIG. 13A including the moveable interface.

FIG. 19G illustrate a subsystem of the femoral preparation and kneedistraction system of FIG. 13A including the resection guide.

FIG. 19H illustrate a subsystem of the femoral preparation and kneedistraction system of FIG. 13A including a torque driver.

FIGS. 20A-20B illustrate the femoral preparation and knee distractionsystem of FIG. 3A.

FIGS. 20C-20D illustrate the femoral preparation and knee distractionsystem of FIG. 13A.

DETAILED DESCRIPTION

This application discloses systems and methods that can be used in aknee joint replacement procedure to measure how soft tissue around theknee acts on the bones of the knee joint. These measurements enable asurgeon to be better informed of the dynamics of the patient's kneejoint anatomy such that preparation of the bones and application of theprosthetic components can be better adapted to the patient, resulting insuperior outcomes.

A. Alignment

1. Femoral and Tibial Systems for Measured Resection

Prior to replacing the knee joint with prosthetic components, surgicalcuts commonly called resections are generally made with a cutting toolor tools along a portion or portions of both the proximal tibia anddistal femur. These cuts are made to prepare the tibia and femur for theprosthetic components. After these cuts are made, the prostheticcomponents can be attached and/or secured to the tibia and femur.

The desired orientation and/or position of these cuts, and of theprosthetic components, can be determined pre-operatively and based, forexample, on a mechanical axis running through an individual patient'sleg. Once the desired locations of these cuts are determinedpre-operatively, the surgeon can use the systems and methods describedherein to make these cuts accurately. While the systems and methods aredescribed in the context of a knee joint replacement procedure, thesystems and/or their components and methods can similarly be used inother types of medical procedures, including but not limited to hipreplacement procedures. U.S. Pat. Nos. 8,998,910, 9,339,226 and8,118,815 disclose additional embodiments of tibial and femoralpreparation system, and are incorporated by reference in their entirety.U.S. Pub. No. 2014/0052149 and U.S. Pub. No. 2016/0242934 discloseadditional features of surgical orientation device and referencesdevices, as well as other components which may be incorporated intosystems described herein, both of which are incorporated by reference.

With reference to FIGS. 1A and 1B, a femoral preparation system 10 canbe used to modify a natural femur with a distal femoral resection,enabling a prosthetic component to be securely mounted upon the distalend of the femur. The femoral preparation system 10 can comprise, forexample, a femoral jig assembly 12, a surgical orientation device 14, areference device 16, a first coupling device 18, and a second couplingdevice 20. The first coupling device 18 can be used to attach thesurgical orientation device 14 to the femoral jig assembly 12. Thesecond coupling device 20 can be used to attach the reference sensordevice 16 with the femoral jig assembly 12.

The surgical orientation device 14 can be used to measure and record thelocation of anatomical landmarks used in a total knee procedure, such asthe location of the mechanical axis of a leg (and femur). “Surgicalorientation device” is a broad term and is to be given its ordinary andcustomary meaning to a person of ordinary skill in the art (i.e. it isnot to be limited to a special or customized meaning) and includes,without limitation, any device that can be used to provide orientationinformation or perform orientation calculations for use in a surgical orother procedure. The mechanical axis of a leg, as defined herein,generally refers to a line extending from the center of rotation of aproximal head of a femur (e.g. the center of the femoral head) through,ideally, the approximate center of the knee, to a center, or mid-point,of the ankle. The mechanical axis of the femur is the same axial lineextending from the center of rotation of the proximal head of the femurthrough the center of the distal end of the femur (the center of distalend of the femur is commonly described as the center of theintercondylar notch). Generally, an ideal mechanical axis in a patientallows load to pass from the center of the hip, through the center ofthe knee, and to the center of the ankle. The surgical orientationdevice 14, in conjunction with the reference device 16 described herein,can be used to locate the spatial orientation of the mechanical axis. Incertain techniques described herein, the surgical orientation device 14and the reference device 16 can be used to locate one, two, or moreplanes intersecting the mechanical axis. The surgical orientation device14 and the reference device 16 can also be used for verifying analignment of an orthopedic fixture or fixtures, or a cutting plane orplanes, during an orthopedic procedure. The surgical orientation device14, and the reference device 16, as described herein, can each be usedalone or in conjunction with other devices, components, and/or systems.

The surgical orientation device 14 can comprise a display 26. Thedisplay 26 can be sized such that a user can readily read numbers,lettering, and/or symbols displayed on the display screen whileperforming a medical procedure. The surgical orientation device 14 canfurther comprise at least one user input device 28. The at least oneuser input device 28 can comprise a plurality of buttons locatedadjacent the display 26. The buttons can be activated, for example, by afinger, hand, and/or instrument to select a mode or modes of operationof the device 14, as discussed further below. The surgical orientationdevice 14 includes a user interface with which a clinician can interactduring a procedure. The surgical orientation device 14 includes anelectrical system. The electrical system can include one or morefeatures including: one or more sensors, an electronic control unit thatcommunicates with one or more sensors, one or more visible alignmentindicators, a power supply, the display 26, memory, one or more userinput devices 28, one or more processors, program logic, other substrateconfigurations representing data and instructions, controller circuitry,processor circuitry, processors, general purpose single-chip ormulti-chip microprocessors, digital signal processors, embeddedmicroprocessors, microcontrollers, other output devices and/or one ormore input/output (“I/O”) ports. In certain embodiments, the electroniccontrol unit can be configured to convert the electronic data from amachine-readable format to a human readable format for presentation onthe display 26. The electronic control unit can communicate withinternal memory and/or the external memory to retrieve and/or store dataand/or program instructions for software and/or hardware. The internalmemory and the external memory can include random access memory (“RAM”),such as static RAM, for temporary storage of information and/or readonly memory (“ROM”), such as flash memory, for more permanent storage ofinformation. In general, the sensor(s) can be configured to providecontinuous real-time data to the surgical orientation device 14. Theelectronic control unit can be configured to receive the real-time datafrom the sensor(s) and to use the sensor data to determine, estimate,and/or calculate an orientation or position of the surgical orientationdevice 14. The orientation information can be used to provide feedbackto a user during the performance of a surgical procedure, such as atotal knee joint replacement surgery, as described in more detailherein.

In some embodiments, in addition or alternatively to the surgicalorientation device 14, electronic equipment can include a display. Theelectronic equipment can include one or more handheld devices such as acomputer, desktop computer, laptop computer, or tablet computer such asan iPad®. In some embodiments, the display is located within thesurgical field. In some embodiments, the display is located outside thesurgical field. In some embodiments, the reference sensor device 16 caninclude a display. In some embodiments, in addition or alternatively tothe surgical orientation device 14, electronic equipment can include atleast one user input device 28. The user input device 28 can beactivated, for example, by a finger, hand, and/or instrument to select amode or modes of operation of one or more electronic devices of thesystem including the surgical orientation device 14 and/or the referencesensor device 16. The electronic equipment can include software and/orhardware for the systems described herein. The electronic equipment caninclude external memory for the systems described herein. The surgicalorientation device 14 and/or the reference sensor device 16 can connectto the internet. The surgical orientation device 14 and/or the referencesensor device 16 can transmit or receive information from the internet.The surgical orientation device 14 and/or the reference sensor device 16can connect to the cloud. The surgical orientation device 14 and/or thereference sensor device 16 can transmit or receive information from thecloud.

In some arrangements, the one or more sensors can comprise at least oneorientation sensor configured to provide real-time data to theelectronic control unit related to the motion, orientation, and/orposition of the surgical orientation device 14. For example, the sensormodule can comprise at least one gyroscopic sensor, accelerometersensor, tilt sensor, magnetometer and/or other similar device or devicesconfigured to measure, and/or facilitate determination of, anorientation of the surgical orientation device 14. In some embodiments,the sensors can be configured to provide measurements relative to areference point(s), line(s), plane(s), and/or gravitational zero.Gravitational zero, as referred to herein, refers generally to anorientation in which an axis of the sensor is perpendicular to the forceof gravity, and thereby experiences no angular offset, for example tilt,pitch, roll, or yaw, relative to a gravitational force vector. In otherembodiments, the sensor(s) can be configured to provide measurements foruse in dead reckoning or inertial navigation systems.

In various embodiments, the sensor(s) comprise one or moreaccelerometers that measure the static acceleration of the surgicalorientation device 14 due to gravity. For example, the accelerometerscan be used as tilt sensors to detect rotation of the surgicalorientation device 14 about one or more of its axes. The one or moreaccelerometers can comprise a dual axis accelerometer (which can measurerotation about two axes of rotation) or a three-axis accelerometer(which can measure rotation about three axes of rotation). The changesin orientation about the axes of the accelerometers can be determinedrelative to gravitational zero and/or to a reference plane registeredduring a tibial or femoral preparation procedure as described herein.

In certain embodiments, a multi-axis accelerometer (such as theADXL203CE MEMS accelerometer available from Analog Devices, Inc. or theLIS331DLH accelerometer available from ST Microelectronics) detectschanges in orientation about two axes of rotation. For example, themulti-axis accelerometer can detect changes in angular position from ahorizontal plane (e.g., anterior/posterior rotation) of the surgicalorientation device 12 and changes in angular position from a verticalplane (e.g., roll rotation) of the surgical orientation device 14. Thechanges in angular position from the horizontal and vertical planes ofthe surgical orientation device 14 (as measured by the sensor can alsobe used to determine changes in a medial-lateral orientation (e.g.,varus/valgus rotation) of the surgical orientation device 14.

In some arrangements, the sensors comprise at least one single- ormulti-axis gyroscope sensor and at least one single- or multi-axisaccelerometer sensor. For example, the sensor can comprise a three-axisgyroscope sensor (or three gyroscope sensors) and a three-axisaccelerometer (or three accelerometer sensors) to provide position andorientation measurements for all six degrees of freedom of the surgicalorientation device 14. In some embodiments, the sensors provide aninertial navigation or dead reckoning system to continuously calculatethe position, orientation, and velocity of the surgical orientationdevice 14 without the need for external references

In one embodiment, a surgical orientation system includes the surgicalorientation device 14 and a reference device 16. The reference device 16can include any of the features of the surgical orientation device 14.The surgical orientation device 14 and/or the reference device 16includes in one embodiment one or more sensors that together can form aninertial measurement unit (IMU). In particular, the IMU includes a firstsensor for determining acceleration and a second sensor for determininggyroscopic positioning. As discussed herein, the first sensor can be anaccelerometer and the second sensor can be a gyroscopic sensor. Thereference device 16 also includes a transmitter for sending data fromthe sensors to the electrical system of the surgical orientation device14. The information received from the reference device 16 can be fed toan input port, or alternatively, the electronic control unit of thesurgical orientation device 14 can itself receive the informationwirelessly. The information from the reference device 16 can correspond,for example, to the position and/or orientation of the reference device16, and can be used by the surgical orientation device 14 to determinean aggregate, relative or overall, position and/or orientation of thesurgical orientation device 14.

The reference sensor device 16 can be used to measure and record thelocation of anatomical landmarks used in a total knee procedure, such asthe location of the mechanical axis of a leg (and femur). “Referencesensor device” is a broad term and is to be given its ordinary andcustomary meaning to a person of ordinary skill in the art (i.e. it isnot to be limited to a special or customized meaning) and includes,without limitation, any device that can be used to reference anotherdevice, and/or to provide orientation information or performcalculations identically or similar to the surgical orientation device14 described above. In some embodiments, the reference sensor device 16can comprise the same or similar components as the surgical orientationdevice 14 described above. Further description of a reference sensor canbe found, for example and without limitation, in paragraphs[0176]-[0178] of U.S. patent application Ser. No. 12/509,388, which isincorporated by reference herein. Additional details of systems,devices, sensors, and methods are set forth in U.S. application Ser. No.10/864,085 filed Jun. 9, 2004, U.S. application Ser. No. 11/182,528filed Jul. 15, 2009, U.S. application Ser. No. 12/557,051 filed Sep. 10,2009, U.S. application Ser. No. 12/509,388 filed Jul. 24, 2009, U.S.application Ser. No. 13/011,815 filed Jan. 21, 2011, U.S. applicationSer. No. 13/115,065, filed May 24, 2011; U.S. application Ser. No.14/399,046 filed Nov. 5, 2014, U.S. application Ser. No. 14/401,274filed Nov. 14, 2014, U.S. application Ser. No. 13/800,620 filed Mar. 13,2013, U.S. application Ser. No. 14/643,864 filed Mar. 10, 2015 and U.S.application Ser. No. 15/550,564 filed Aug. 11, 2017, which are allincorporated by reference herein in their entireties for all purposes.

Referring to FIG. 1C, the femoral jig assembly 12 can comprise anorthopedic assembly for femoral preparation during a total kneereplacement procedure. In a preferred arrangement, the femoral jigassembly 12 can comprise a distal guide assembly 88, a microblockassembly 90, a cutting block 92, an articulating arm 98, and a midlinepin 102. In preparation for the distal femoral resection, the method canbegin with locating a distal point that is intersected by the mechanicalaxis of the femur. The method can comprise installing the femoral jigassembly 12 via the midline pin 102 in the approximate center of theintercondylar notch, which places the femoral jig assembly 12 in anapproximate center position of the distal end portion of the femur.

The reference sensor device 16 and/or orientation device 14 can be usedto determine the relative coordinates of a center pivot point on thefemur. By determining the coordinates of the pivot point of the femoralhead, the reference sensor device 16 and/or surgical orientation device14 can calculate the location and/or orientation of the mechanical axisthat extends through the femur.

In order to determine the coordinates of the pivot point of the femoralhead (i.e. the pivot point of the mechanical axis), the leg can be moved(e.g. swung). For example, the leg can be moved in several differentdirections and/or planes, with the reference sensor device 16 and/orsurgical orientation device 14 attached. Readings such as angular rateand acceleration (“surgical orientation device 14 and/or referencesensor device 16 data”) of the femur 140 can be obtained by thereference sensor device 16 and/or surgical orientation device 14 untilthe location and/or orientation of the mechanical axis of the leg andthe femur 140 (“femoral mechanical axis”) is found. In one embodiment,where one or more multi-axis (e.g., two-axis) accelerometers andgyroscopes are used, surgical orientation device 14 and/or referencesensor device 16 data for each movement of the femur 140 can benumerically integrated over time to obtain a trajectory of position andvelocity points (one point for each IMU data). The IMU data can beintegrated without imposing any plane trajectory constraints onmovements of the femur 140.

The acceleration and angular rate sensed by the reference sensor device16 and/or surgical orientation device 14 during the leg movement can beprocessed while the leg is moved about its pivot point. The referencesensor device 16 and/or surgical orientation device 14 can provide anoutput vector representing the center of the rotation with respect tothe inertial sensor axes of the reference sensor device 16 and/orsurgical orientation device 14.

In some embodiments, prior to determining the location and/ororientation of the center of rotation of the mechanical axis, an errorcorrection technique can be used to remove biases in the surgicalorientation device 14 and/or reference sensor device 16. For example, anerror correction technique can include assessing 1) static bias; 2)gyroscopic bias; and 3) accelerometer bias in the surgical referencesensor device 16 and/or surgical orientation device 14.

At least one purpose of the surgical orientation device 14 and/orreference device 16 and systems described herein is to provide guidanceto the surgeon as to how to position a cutting block on the bone inorder to achieve a cutting plane that is perpendicular to the loadbearing axis of the bone (or some number of degrees off of thatperpendicular plane if desired). A jig, such as that described above,can be fixed to the bone to be cut and the reference sensor device 16and surgical orientation device 14 can be attached to that jig (onedevice is attached to a fixed portion of the jig to act as a referenceto the bone's orientation and the other device is attached to anarticulating arm of the jig to provide the surgeon a means to find andset the desired cutting plane). The articulating arm of the jig can beconstrained to only be moved in two dimensions, e.g., pitch and yaw (notrotation). These two axes form a plane that can be adjusted to guide theplacement of the cutting block which guides the saw to cut the bone onthat plane.

Once biases have been removed, and the reference sensor device 16 and/orsurgical orientation device 14 has calculated the pivot point of themechanical axis as described above and located the mechanical axis, theuser can begin adjusting and orienting the cutting block 92 relative tothe location of the mechanical axis. For example, the surgicalorientation device 14 can display the varus/valgus and flexion/extensionangle adjustments needed for the surgical orientation device 14 (and thefemoral jig assembly 12) to reach neutral alignment with the mechanicalaxis that passes through the femoral head.

Advantageously, in some embodiments the reference sensor device 16 canenable the procedure to proceed without fixation of the leg beingoperated upon because the reference sensor device 16 can track therelative positions of the leg, e.g. of the femur. For example, at leastone of the reference sensor device 16 and the surgical orientationdevice 14 can communicate with the other, such that any relativemovement of one of the devices can be tracked by the other, and theresulting overall orientation of the reference sensor device 16 and/orsurgical orientation device 14 can be displayed on display 26 of thesurgical orientation device 14. In some embodiments, the referencesensor device 16 can track movement of the leg (i.e. femur or tibia),such that if the leg moves during a procedure, the overall orientationof the surgical orientation device 14 can remain accurate.

Referring to FIG. 2A, a tibial preparation system 210 can be used formodifying a natural tibia with a proximal tibial resection to enable aprosthetic component to be securely mounted upon the proximal end of thetibia. The tibial preparation system 210 can comprise, for example, atibial jig assembly 212, a landmark acquisition assembly 214, thesurgical orientation device 14, and the reference sensor device 16.

The tibial jig assembly 212 can comprise an orthopedic assembly for usein preparing a tibia for a prosthetic component, and in particular formaking angular adjustments relative to an anatomical feature.

In a preferred arrangement, the tibial jig assembly 212 can comprise acomponent for adjusting a posterior/anterior slope of the surgicalorientation device 14 and/or a cutting block. In a preferredarrangement, the tibial jig assembly 212 can also comprise a componentfor adjusting the varus/valgus slope of a cutting block.

FIG. 2A illustrate various features of the landmark acquisition assembly214. The landmark acquisition assembly 214 can comprise a structure thatis configured to contact and/or obtain information about anatomicallandmarks on the human body. The landmark acquisition assembly 214 canbe attached to or form part of the tibial jig assembly 212.

Referring to FIG. 2A, the probe assembly 202 can include an elongatemember 220. The probe assembly 202 can comprise a probe member 206 thatis located on at least one end of the elongate member 220. The probemember 206 can be configured to contact an anatomical landmark, such asfor example a malleolus on a patient's ankle. The elongate member 220can further comprise a series of markings 227, indicating distanceand/or length. The markings can be used to measure, for example, an APoffset of the probe member 206.

The midline reference probe assembly 226 can be positioned at anappropriate anatomical location at the proximal tibia, for example at apoint just posterior to the insertion of the anterior cruciate ligament(ACL), or at another suitable anatomical landmark. For example, a tip241 of the midline reference probe assembly 226 can be resting over theinsertion point of the anterior cruciate ligament in the knee, and/or asoft point on the top of the tibia commonly referred to as the A/P pointof the mechanical axis. This point is generally located along a tibialspine on top of the tibia, and marks the location of a point along themechanical axis of the leg. Indicia of distance on an upper surface ofthe midline reference probe assembly 226 (e.g. via markings 240) can benoted and a corresponding A/P offset position can be set in the landmarkacquisition assembly 214 (e.g. via markings 227 described above).

FIG. 2A illustrates the tibial jig assembly 212 fully assembled with areference sensor device 16 coupled to the reference sensor deviceinterface 228 and with a surgical orientation device 14 coupled with theorientation device interface 230.

Referring to FIG. 2B, the method can further comprise acquiringlandmarks to determine the location of the mechanical axis passingthrough the tibia. For example, landmarks can be acquired by engagingthe probe member 206 of probe assembly 202 first with a medialmalleolus, and then with the lateral malleolus (or vice versa). FIG. 2Billustrates acquisition of one malleolus. Acquisition of the othermalleolus can similarly be accomplished by swinging a portion orportions of the tibial jig assembly 212 such that the probe member 206contacts the other side of the leg. Thereafter, the surgical orientationdevice 14 can determine the location of the mechanical axis, e.g., bylocating sagittal and coronal planes extending through the mechanicalaxis. In some embodiments, the surgical orientation device can calculatethe location of the mechanical axis by assuming that the mechanical axisextends from the point of contact of the midline reference probeassembly 226 with the proximal tibia through a point that is halfwaybetween the two malleolus points contacted by the probe member 206 oneither side of the leg, or any other appropriate point.

In some embodiments, the user can activate the surgical orientationdevice 14, such as by pressing one of the user inputs 28 on the surgicalorientation device 14, during each landmark acquisition. Once activated,the, surgical orientation device 14 can register (e.g. record) theorientation of the surgical orientation device 14 as a referenceposition (e.g. a first reference position). For example, the surgicalorientation device 14 can register and/or calculate the currentorientation of the surgical orientation device 14 based on datacollected from the sensor(s) inside the surgical orientation device 14.The orientation of the surgical orientation device 14 in a firstreference position can be used to identify and register the orientationof a coronal plane which contains the mechanical axis of the leg, aswell as to determine a first reference point for identifying thelocation and/or orientation of a sagittal plane containing this samemechanical axis.

The user can then swing the probe member 206 over to the other (e.g.medial) side of the leg, such that the reference probe 206 is locatedadjacent the other malleolus. During each landmark acquisition, the usercan palpate the ankle. Once the location of the other (e.g. medial)malleolus is identified, the user can press one of the user inputs 28 onthe surgical orientation device 14 to cause the surgical orientationdevice 14 to determine the orientation of the surgical orientationdevice 14 in a second reference position. For example, the surgicalorientation device 14 can register and/or calculate the currentorientation of the surgical orientation device 14 based on datacollected from the sensor(s) inside the surgical orientation device 14.

The orientation of the surgical orientation device 14 in the secondreference position can again be used to identify the orientation of acoronal plane extending through the tibia that contains the mechanicalaxis of the leg, and/or can be used to locate a second reference pointfor identifying the location and/or orientation of a sagittal planecontaining the same mechanical axis.

When using the surgical orientation device 14 to determine the first andsecond reference positions, output of the sensor(s) in the surgicalorientation device 14 can be monitored in a manner that minimizes errorin the reading. For example, a transient phase can be eliminated in theoutput of the sensors to arrive at an accurate estimation of the givenanatomical landmark.

Once information about both the first and second reference positions hasbeen acquired and registered in the surgical orientation device 14, thesurgical orientation device 14 can determine (e.g. calculate) thelocation of a desired plane between the lateral malleolus and the medialmalleolus. The desired plane can correspond to the sagittal planecontaining the mechanical axis. The desired plane can vary, depending onfactors such as the patient's specific anatomy and the surgeon'straining and experience. For example, the desired plane can be locatedmidway between the lateral malleolus and medial malleolus, or 55% towardthe medial malleolus from the lateral malleolus, or at some otherpredetermined location.

The user can use one or more user inputs 28 to direct the surgicalorientation device 14 to calculate the location of and/or orientation ofthe sagittal plane. Once the surgical orientation device 14 hascalculated where the sagittal plane is, the surgical orientation device14 can provide location feedback to the user, for example in the form ofa visual signal or signals on the display 26, indicating that thelocation of the sagittal plane has been calculated.

Referring to FIG. 2C, once the mechanical axis has been identified, thetibial cutting block assembly 224 can be utilized. The cutting blockassembly 224 can be positioned such that the cutting block 232 is spacedaway from anterior surface of the tibia. The surgical orientation device14, and tibial assembly 212, can be used to adjust the cutting block 232in order to obtain a desired orientation for resection of the top of thetibia. For example, a posterior slope assembly 216 and a varus/valgusassembly can each be independently adjusted to change the angle of thecutting block 232, and subsequently, the angle of the intendedresection. During this adjustment, the surgical orientation device 14can provide a reading or readings on its display 26 indicating whetherthe surgical orientation device 14 (and likewise the cutting block 232)is aligned with the sagittal plane and/or coronal plane containing themechanical axis.

Once the cutting block is in position, the cutting block 232 can bemounted to an anterior surface of a proximal portion of the tibia by aplurality of pins. The surgical orientation device 14 can be removed, ascan the tibial assembly 212. After the cutting block 232 has beenmounted to the tibia, a proximal portion of the tibia can be resected.

B. Femoral Preparation and Knee Distraction System

FIGS. 3A-3E show an embodiment of a resection plane orienting system310. The system 310 can be configured to distract the knee joint duringa knee replacement procedure. The system 310 can be configured todistract the knee joint during a knee replacement procedure and measurethe native or pre-surgical rotation of the femur relative to the tibialresection. The system 310 can additionally or alternatively beconfigured to facilitate attachment of a drill guide to the distal femurfor alignment of locating holes in the distal femur for the implant's“4-in-1” cutting block. When the knee is sufficient distracted, thesystem 310 provides information about how to resect the femur in a waythat helps to balance the soft tissue and/or ligaments within the kneejoint. The system 310 can comprise the surgical orientation device 14and the reference sensor device 16. As described herein, the surgicalorientation device 14 and the reference sensor device 16 can be used foralignment, for distraction or for both alignment and distraction. Thesystem 310 can further comprise one or both of a tibial system 312 and afemoral system 352, as described herein. While the tibial system 312 anda femoral system 352 are described as discrete subsystems, the system310 can be considered one instrument. In some embodiments, the system310 can be pre-connected on a surgical kit, e.g. implemented as aninseparable assembly.

1. Tibial System

FIGS. 4A and 4B illustrate the tibial system 312. The tibial system 312can include a tibial baseplate 314. The tibial baseplate 314 can beconsidered a reference feature. The tibial baseplate 314 can beconfigured to be positioned on a tibial plateau or on a resection planeformed on the proximal tibia. The tibial baseplate 314 can comprise aplanar member. The tibial baseplate 314 can comprise a first surface 318configured to align with the flat surface of the resected tibia. Thetibial baseplate 314 can include a second surface 316, opposite thefirst surface 318 positioned toward the femur. The tibial system 312 caninclude an extension member 320. The tibial system 312 can include amounting block 322. The extension member 320 can span between themounting block 322 and the tibial baseplate 314. The extension member320 can position the mounting block 322 away from, e.g., anteriorly of,the knee joint.

In some embodiments, the extension member 320 can be integrally ormonolithically formed with the tibial baseplate 314. In someembodiments, the extension member 320 and the tibial baseplate 314 forma unitary structure. In some embodiments, the extension member 320 canbe integrally or monolithically formed with the mounting block 322. Insome embodiments, the extension member 320 and the mounting block 322form a unitary structure. In some embodiments, one or more of theextension member 320, the tibial baseplate 314, and the mounting block322 are separate components.

The mounting block 322 can include a first coupler 324. The firstcoupler 324 can be configured to couple with the surgical ordinationdevice 14 and/or the reference sensor device 16. The first coupler 324can include an elongate post. In some embodiments, the first coupler 324can have a regular shape (e.g., cylindrical). In some embodiments, thefirst coupler 324 have an irregular shape (e.g., triangular, teardrop,elliptical, rectangular). The irregular shape may facilitate alignmentof the reference sensor device 16 in one orientation relative to themounting block 322. In the illustrated embodiment, the first coupler 324is positioned on a bottom surface of the mounting block 322. In theillustrated embodiment, the first coupler 324 is positionedperpendicular to the tibial resection. In some methods of use, thetibial resection is the reference feature. In the illustratedembodiment, the first coupler 324 is positioned such that thelongitudinal axis of the reference sensor device 16 aligns with thelongitudinal axis of the tibia. The axis of the tibia can beperpendicular to the tibial resection. In the illustrated embodiment,the first coupler 324 is positioned such that the longitudinal axis ofthe reference sensor device 16 aligns with a mechanical axis associatedwith the knee joint, e.g., of the tibia or the leg.

In some embodiments, the mounting block 322 can include one or moreadditional couplers 326. The one or more additional couplers 326 can beidentical to the first coupler 324. The one or more additional couplers326 can be positioned on any surface of the mounting block 322. Anadditional coupler 326 can be positioned such that the longitudinal axisof the reference sensor device 16 is perpendicular to the longitudinalaxis of the tibia. See FIG. 11B. An additional coupler 326 can bepositioned such that the longitudinal axis of the reference sensordevice 16 is perpendicular to the mechanical axis. An additional coupler326 can be positioned perpendicular to the tibial resection plane. Anadditional coupler 326 can be positioned at any known angle from thetibia resection plane. One or more of the couplers 324, 326 can beparallel to the tibial resection plane. One or more of the couplers 324,326 can be perpendicular to the tibial resection plane. The coupler 324can arrange the reference sensor 16 perpendicular to the tibialresection plane. The couple 326 can arrange the reference sensor 16parallel to the tibial resection plane. The orientation of the referencesensor 16 relative to the tibial resection plane can be an input in thesystem 310. The user can input the orientation of the reference sensor16 as an input in the surgical orientation device 14. The couplers 324,326 can work with different software versions that accommodate theirarrangement. In some embodiments, the coupler 326 can be providedwithout also providing the coupler 324.

The mounting block 322 can include a guide portion 330. In someembodiments, the guide portion 330 can extend through the mounting block322. In some embodiments, the guide portion 330 is a slot or otheropening. The guide portion 330 can guide a post 332 through the mountingblock 322. The guide portion 330 can be configured to allow the post 332to slide through the mounting block 322. The post 332 can provide formovement of the femoral system 352 relative to the tibial system 312.

The system 310 can include an adjustment device 336. The adjustmentdevice 336 can be positioned anywhere within the system 310. In theillustrated embodiment, the tibial system 312 can include the adjustmentdevice 336. The adjustment device 336 is configured to translate thepost 332 relative to the mounting block 322. The adjustment device 336can include a gear. The post 332 can include a corresponding gear,screw, ramp, rack, etc. The adjustment device 336 can include a pinion.The post 332 can include a corresponding rack. In the illustratedembodiment, the adjustment device 336 is a drive pinion. The adjustmentdevice 336 can include any mechanical feature configured to causetranslation of the post 332. In some embodiments, the adjustment device336 can be rotated to cause translational movement of the post 332. Insome embodiments, the adjustment device 336 can be translated to causetranslational movement of the post 332. Other adjustment devices arecontemplated. The adjustment device 336 can include an interface 338.The interface 338 can allow the user to move the adjustment device 336.The interface 338 can include a knob. The interface 338 can include arecess. In the illustrated embodiment, the interface 338 is a hexrecess. The interface 338 can allow rotation of the adjustment device336 by the user.

FIGS. 4A and 4B illustrate the tibial system 312 and the post 332. FIGS.5A-5D illustrates internal components of the tibial system 312 and thepost 332. In some embodiments, the post 332 is substantially straightalong its length. The post 332 can be translated by the adjustmentdevice 336. The post 332 can include a rack 334. The rack 334 can extendalong an edge of the post 332. The rack 334 can extend along the lengthof the post 332, or a portion thereof. The adjustment device 336 can bedrive pinion. The adjustment device 336 can interact with the rack 334such that rotation of the adjustment device 336 causes translation ofthe post 332. The adjustment device 336 can be free to rotate within themounting block 332. The adjustment device 336 can be prevented fromtranslation within the mounting block 332.

The post 332 can include one or more markings 340. The marking 340 canindicate length or extension of the post 332. The marking 340 canindicate a distraction distance of the system 310, as described herein.The marking 340 can include a scale. The marking 340 can include amachine readable scale. The marking 340 can include a scale visible tothe user. The scale visible to the user is shown in FIGS. 4B, 5B and 5D.The scale extends beyond the mounting block 332. The user can view thescale to indicate the distraction distance. The mounting block 332 caninclude indicia, such as an arrow, to direct the user visually towardthe measurement. As the post 332 translates upward, the numbers of thescale visible to the user increases (e.g., 8 mm, 9 mm, 10 mm, etc.). Thedistraction distance can correspond to the measurement visible to theuser on the scale. In some embodiments, the marking 340 can be over arange of from about 0.5 inches to 3 inches, approximately 0-5 inches,etc. The marking 340 can be printed on the post 332. In someembodiments, the marking 340 can be on a separate component such as aninlay 342. The inlay 342 can be received within a portion of the post332. In some embodiments, the inlay 342 is separated a distance from thedistal end of the post 332. In some embodiments, the inlay 342 isseparated a distance from the proximal end of the post 332.

In some embodiments, the marking 340 can include a machine readablefeature disposed on a surface of the post 332. In some embodiments, themachine readable feature comprises a binary code, a two dimensional barcode, or other symbol. In some embodiments, the reference sensor device16 shown, in FIG. 3A, is configured to be positioned to read themarkings 340. The reference sensor device 16 can be adapted to opticallydetect the machine readable feature of the markings 340. The markings340 can include a binary code or other symbol that the reference sensordevice 16 can read. The markings 340 can include a scale. In someembodiments, the scale can be read by the reference sensor device 16. Insome embodiments, the scale is obstructed from the user. The distanceindicated on markings 340 can be an input into the system 310 in any ofthe manners discussed herein (e.g., manual or sensed).

FIGS. 6A and 6B illustrate an embodiment of the reference sensor device16. The reference sensor device 16 can includes a camera 344. In someembodiments, the camera 344 and the reference sensor device 16 areseparate components. In some embodiments, the camera 344 and thereference sensor device 16 are coupled together. In some embodiments,the camera 344 is integrally formed with the reference sensor device 16.In some embodiments, the camera 344 is a separate component from thereference sensor device 16. The reference sensor device 16 can include awindow 346 to enable the camera 344 to view there through. The camera344 can capture images of the marking 340. In some embodiments, thecamera 344 and/or the reference sensor device 16 can include a light toilluminate the marking 340. In some embodiments, the light is a LED. Insome embodiments, the mounting block 322 includes a window to permit thecamera 344 to capture images. In other embodiments, the camera 344captures images of the marking 340 extending beyond the mounting block322.

The image of the marking 340 can provide accurate determination of thetranslational position of the post 332. The marking 340 can bepositioned on the post 332 adjacent to the camera 344 when the referencesensor device 16 is coupled to the mounting block 322. The camera 344can be fixed relative to the mounting block 322 when the camera 344captures images. The camera 344 can be oriented such that the camera 344faces the marking 340. The camera 344 can capture an image of themarkings 340. The image can correspond with a distraction distance. Thedistraction distance changes as the post 332 slides through the mountingblock 322.

In some embodiments, the camera 344 can capture an image of a binarycode of the marking 340. In some embodiments, the camera 344 can capturean image of a scale or other markings 340. The distraction distance canbe based on images captured by the camera 344 of the marking 340, asdescribed herein. In some embodiments, the image can be capturedautomatically by the camera 344. In some embodiments, the image can becaptured by the camera 344 when prompted by the user (e.g., interactionwith the user input 28).

In some embodiments, the system 310 can measure the distraction distanceusing one or more sensors. The reference sensor device 16 can includeone or more inertial sensors capable of determining a distancemeasurement. The surgical orientation device 14 can include one or moreinertial sensors capable of determining a distance measurement. In someembodiments, the system 310 can measure a reference distance from thesurgical orientation device 14 and/or the reference sensor device 16. Insome embodiments, the system 310 can record or store a referencedistance from the surgical orientation device 14 and/or the referencesensor device 16. During distraction, the system 310 can measure changesin distance from the reference distance. The inertial sensor output canbe used to measure distance in addition to or alternatively to thecamera 344 reading the markings 340. The system 310 can perform one ormore calculations to determine the distraction distance from theinertial sensor output.

Referring back to FIGS. 4A-5D, the system 310 can include a catch 348.The catch 348 can be positioned anywhere within the system 310. In theillustrated embodiment, the tibial system 312 can include the catch 348.The catch 348 is configured to maintain the position of the post 332relative to the mounting block 322. The catch 348 can include a gear.The catch 348 can include a detent. The catch 348 can include a pin. Thepost 332 can include a corresponding gear, screw, ramp, rack or ratchet.The catch 348 can include any mechanical feature configured to limitmovement of the post 332. In some embodiments, the catch 348 can includeany mechanical feature configured to limit unidirectional movement ofthe post 332.

The post 332 can include a ratchet 350. The ratchet 350 can extend alongthe length of the post 332, or a portion thereof. The catch 348 caninteract with the ratchet 350 such that translation of the post 332 canbe limited. In some embodiments, when the catch 348 is engaged with theratchet 350, the translation of the post 332 can be limited in bothdirections. When the catch 348 is disengaged with the ratchet 350, thepost 332 can translate in both directions via the adjustment device 336.In some embodiments, the catch 348 can be engaged or disengaged by theuser interacting with an interface, such as by turning a knob. In someembodiments, the catch 348 limits movement in only one direction. Whenthe catch 348 is engaged with the ratchet 350, the translation of thepost 332 can be limited to movement in one direction. In someembodiments, the one direction increases the distraction distance. Whenthe catch 348 is disengaged with the ratchet 350, the post 332 cantranslate in both directions via the adjustment device 336.

In some embodiments, the catch 348 can include a spring. In someembodiments, the catch 348 can be biased into engagement with theratchet 350. The user interacts with the interface to move the catch 348away from the ratchet 350. In some embodiments, the catch 348 can bebiased out of engagement with the ratchet 350. The user interacts withthe interface to move the catch 348 toward the ratchet 350. Otherconfigurations are contemplated.

In some embodiments, the movement of the post 332 can be tracked ormonitored. For example, the system 310 can provide audible and/or visualfeedback to the user, indicating the degree or extent to which the post332 has been moved relative to an initial starting position. In someembodiments, a feedback system can be coupled to the post 332. In someembodiments, the catch 348 is the feedback system. In other embodiments,the system 310 can include another feedback system. In some embodiments,the user can hear and/or feel the catch 348 contacting the ratchet 350as the post 332 moves up and/or down. This contact can produce anaudible click, or clicks. This contact can additionally or alternativelyprovide a force (e.g. frictional) which can hold the post 332 in adesired position, until the adjustment device 336 is turned again.

2. Femoral System

FIGS. 7A and 7B illustrate the femoral system 352. The femoral system352 can include a femoral baseplate 354. In the illustrated embodiment,the femoral baseplate 354 can include one femoral baseplate 354. In someembodiments, the femoral baseplate 354 can include two or more femoralbaseplates 354. In some embodiments, the femoral baseplate 354 is thefemur contacting component. The femoral baseplate 354 can comprise aplanar member. The femoral baseplate 354 can comprise a first surface358 configured to be positioned relative to a portion of the femur. Forexample, the first surface 358 of the femoral baseplate 354 can beconfigured to engage the bottom of a bony landmark, such as for examplea femoral condyle. The femoral baseplate 354 can include a secondsurface 356, opposite the first surface 358 positioned toward the tibia.

The femoral system 352 can include an extension member 360. In theillustrated embodiment, the extension member 360 is generally L-shaped.The extension member 360 can include a first portion 362 that extendsfrom the femoral baseplate 354. The extension member 360 can include asecond portion 364 that extends perpendicularly or generallyperpendicularly from the first portion 362. Other configurations of theextension member 360 are contemplated. In some embodiments, theextension member 360 can be integrally or monolithically formed with thefemoral baseplate 354. In some embodiments, the extension member 360 andthe femoral baseplate 354 form a unitary structure. The rotation of thefemoral baseplate 354 can cause corresponding rotation of the extensionmember 360 as described herein.

The femoral system 352 can include a post mount 366. The extensionmember 360 can span between the post mount 366 and the femoral baseplate354. The extension member 360 can position the post mount 366 away fromthe knee joint. The femoral system 352 can include the post 332described herein. In some embodiments, the post mount 366 can be coupledto the post 332. In some embodiments, the post mount 366 can beintegrally or monolithically formed with the post 332. In someembodiments, the post mount 366 and the post 332 form a unitarystructure. The translation of the post 332 can cause correspondingtranslation of the post mount 366 as described herein.

The post mount 366 can be coupled to the extension member 360. The postmount 366 can be coupled to the second portion 364 of the extensionmember 360. The post mount 366 can be mounted to allow rotation of theextension member 360 relative to the post mount 366. The post mount 366can be mounted to allow rotation of the femoral baseplate 354 relativeto the post 332. The femoral system 352 can include a rotationalinterface 368. The rotational interface 368 can be a pin. The extensionmember 360 can rotate about the rotational interface 368 relative to thetibial baseplate 314. The femoral baseplate 354 can rotate about therotational interface 368 relative to the tibial baseplate 314. Therotational interface 368 can be positioned in the middle of the femurand/or tibia. The rotational interface 368 can be aligned with ananatomical feature, such as the intercondylar notch, Whiteside's Line,or the mechanical axis of the tibia.

The rotational interface 368 can include a mounting feature 370. Themounting feature 370 can allow one or more drill guides or otherinstruments to mount to the system 310. The mounting feature 370 can beparallel to the tibial baseplate 314. The mounting feature 370 can becoupled to the post 332. In some embodiments, the mounting feature 370remains in position as the femoral baseplate 354 rotates. The mountingfeature 370 can be decoupled from the rotation of the extension member360. The mounting feature 370 can be decoupled from the rotation of thefemoral baseplate 354.

The extension member 360 can include a second coupler 374. The secondcoupler 374 can be configured to couple with the surgical orientationdevice 14 and/or the reference sensor device 16. The second coupler 374can include an elongate post. In some embodiments, the second coupler374 can have a regular shape (e.g., cylindrical). In some embodiments,the second coupler 374 can have an irregular shape (e.g., triangular,teardrop, elliptical, rectangular). The irregular shape may facilitatealignment of the surgical orientation device 14 in one orientationrelative to the extension member 360. In the illustrated embodiment, thesecond coupler 374 is positioned on a side surface of the second portion364. In the illustrated embodiment, the second coupler 374 is positionedsuch that the longitudinal axis of the surgical orientation device 14aligns with the femoral baseplate 354. As the femoral baseplate 354rotates relative to the tibial baseplate 314, the surgical orientationdevice 14 rotates. As the femoral baseplate 354 translates relative tothe tibial baseplate 314, the surgical orientation device 14 translate.

Referring back to FIG. 3E, the femoral system 352 can include a bracket376. The second coupler 374 can be configured to couple with the bracket376. The surgical orientation device 14 can be configured to couple withthe bracket 376. The bracket 376 can include a third coupler 378. Thethird coupler 378 can be configured to couple with the surgicalorientation device 14 and/or the reference sensor device 16. The thirdcoupler 378 can have the same shape and/or configuration as the firstcoupler 324 and/or the second coupler 374. In the illustratedembodiment, the third coupler 378 is positioned on a side surface of thebracket 374.

In some method of use, the surgical orientation device 14 is coupledwith the second coupler 374 and the reference sensor device 16 iscoupled to the third coupler 378. The surgical orientation device 14 andreference sensor device 16 at a fixed angle and both coupled to thefemur. The surgical orientation device 14 and the reference sensordevice 16 can be calibrated relative to the femur. The surgicalorientation device 14 and the reference sensor device 16 can be zeroed.The role of the third coupler 378 is to hold the surgical orientationdevice 14 and reference sensor device 16 at some known angle duringcalibration or zeroing. The user can move the reference sensor device 16to the first coupler 324 described herein. The reference sensor device16 is coupled to the tibia via the first coupler 324. Thereafter, thesurgical orientation device 14 and/or the reference sensor device 16 cancalculate changes in position and/or orientation relative to each other.The surgical orientation device 14 and/or the reference sensor device 16calculate changes in angle relative to each other. The surgicalorientation device 14 and/or the reference sensor device 16 can use gyropropagation to measure the coronal plane angle. The surgical orientationdevice 14 and/or the reference sensor device 16 can include softwareand/or hardware to perform the gyro propagation. The surgicalorientation device 14 and/or the reference sensor device 16 can includeone or more algorithms to calculate the angle of the surgicalorientation device 14 as the surgical orientation device 14 rotates withthe femoral baseplate 354.

FIG. 3E shows a perspective view of the system 310. As shown in FIGS.3E, 8A, and 8B, femoral system 352 can comprise a drill guide 380. Thedrill guide 380 can include one or more openings 382. The openings 382can extend through the entire drill guide 380. While a plurality ofopenings 382, different numbers, sizes, shapes, and/or locations ofopenings 382 can also be used. The openings 382 can be used as guidesfor drills and/or pins. For example, when the system 310 has distracteda distal femoral condyle or condyles in a knee replacement procedure, apin or pins (not shown) can be inserted into the distal femur in orderto provide a mounting location for a cutting block (not shown). Theopenings 382 can be used as guides for insertion of these pins.

The openings 382 can be spaced apart from one another in a pattern orpatterns. For example, some of the openings 382 along the bottom of thedrill guide 380 can be spaced slightly higher, and/or further away fromthe tibial baseplate 314 than other openings along the bottom of thedrill guide 380. Similarly, some of the openings 382 along the top ofthe drill guide 380 can be spaced slightly higher, and/or further awayfrom the tibial baseplate 314 than other openings 382 along the top ofthe drill guide 380. In some embodiments, one or more parallel rows ofopenings 382 are provided. The rows can be parallel to the tibialbaseplate 314. The one or more parallel rows of openings 382 can allowthe user to adjust the gap, as described herein. The one or moreparallel rows of openings 382 can allow the user to adjust the cuttingblock by a known distance. The one or more parallel rows of openings 382can be used, for example, to control the orientation of a cutting blockwhich is later attached to the pins.

In some embodiments, the drill guide 380 can have two orientations. Thedrill guide 380 can provide openings for even measurements (e.g., 2 mm,4 mm, 6 mm, etc.). The drill guide 380 can be inverted for oddmeasurements (e.g., 1 mm, 3 mm, 5 mm, etc.). The drill guide 380 caninclude a first leg 384 and a second leg 386. The first leg 384 cancouple with the mounting feature 370. The second leg 386 can couple withthe mounting feature 370. In some embodiments, when the first leg 384 iscoupled with the mounting feature 370, the user can utilize the evenmeasurements. The first leg 384 is shown coupled to the mounting feature370 in FIG. 8B. In some embodiments, when the second leg 386 is coupledwith the mounting feature 370, the user can utilize the oddmeasurements. The drill guide 380 can include one or more markings 388.The marking 388 can indicate a value related to the opening 382. Themarking 388 can indicate a distance measurement related to the opening382. In FIG. 8B, the markings 388 for even measurements are inverted forthe odd measurements. In some embodiments, each opening 382 has twomarkings 388. In some embodiments, each opening 382 has two markings 388and only one is readable to the user. In some embodiments, each opening382 has two markings 388 and one is inverted. In some embodiments, eachopening has two markings 388 and only one is readable based on theorientation of the drill guide 380.

Referring to FIGS. 3E and 7A, the drill guide 380 can be a modulardevice that can be coupled or decoupled from the mounting features 370.In some embodiments, the mounting features 370 can be coupled to therotational baseplate 368. In some embodiments, the rotational baseplate368 is coupled to the post 332. In some embodiments, the post 332 iscoupled to the tibial baseplate 314. In some embodiments, the drillguide 380 can be stabilized relative to the tibial baseplate 314. Thedrill guide 380 can be rotationally coupled to the tibial baseplate 314.The drill guide 380 can be parallel to the tibial baseplate 314. In someembodiments, the rotation of the femoral baseplate 354 is independent ofthe positioning of the drill guide 380. The system 310 can provide analignment of the drill guide 380 relative to the tibial baseplate 314 asdescribed herein.

In some embodiments, the system 310 can further comprise a spring orsprings (not shown) which can apply a constant spring force to whateveranatomical structure or structures the femoral baseplate 354 arecontacting. For example, the system 310 can include a pre-tensionedspring, such that when the system 310 is placed into an anatomical joint(e.g. a knee joint), the pre-tensioned springs can be released, and apre-determined force can be applied by the femoral baseplate 354 to anycontacted anatomical structures (e.g. condyles). In some embodiments,the force applied can be approximately 70-80 N. In other embodiments theforce applied by can be approximately 60-90 N. Other forces and/or forceranges are also possible. The force applied by each spring can bedifferent. In some embodiments, the system 310 does not include one ormore springs applying the distraction force. The distraction force canbe provided solely by the post 332 described herein. Possibledisadvantages of springs include that the force is not constant over arange of distraction distance. The post 332 can provide a constant forceover a range of distraction distances. Possible disadvantages of springsinclude that the force is not controlled and/or limited by the surgeon.Possible disadvantages to springs include that springs could more easilycause injury to ligaments. The posts 332 can provide a force that iscontrolled and/or limited by the user.

The system 310 described above can be biocompatible for short termexposure to the inner anatomy of the knee or other body joint, and canbe sterilized by autoclave and/or gas. The system 310, or other similardistraction devices, can be used in joints other than the knee joint.For example, the system 310 can be used in the elbow, or other joint, todistract a joint.

3. Distraction Overview

FIG. 9A-9C illustrate additional views of the system 310 mounted on thetibia and femur of a patient. FIG. 9A illustrates an initial position ofthe system 310. FIGS. 9B and 9C illustrate subsystems of the system 310.In some embodiments, the tibial baseplate 314 can be adjacent to thefemoral baseplate 354. In some embodiments, the extension 320 can beadjacent to the extension 360. In some embodiments, the post mount 366can be adjacent to the mounting block 322. The surgical orientationdevice 14 can be coupled to the second coupler 374, see also FIG. 7A.The reference sensor device 16 can be coupled the first coupler 324, seealso FIG. 4A. The reference sensor device 16 can be coupled theadditional coupler 326, see also FIG. 11A. As noted herein, the firstcoupler 324, the second coupler 326 and/or the third coupler 378 can bealigned along the mechanical axis. The additional coupler 326 can be atsome angle relative to the mechanical axis, such as perpendicular to themechanical axis.

FIG. 9A illustrate how the tibial system 312 and the femoral system 352can function together. The femoral system 352 can be moved up and down(e.g. proximally and distally) relative to the tibial baseplate 314 bythe adjustment device or devices 336. The adjustment device 336 can beused to dictate and/or facilitate movement of the femoral system 352.The adjustment device 336 can include an interface 338 that allows theuser to rotate the adjustment device 336, see FIG. 4A. The adjustmentdevice 336 can be located within the mounting block 322. The mountingblock 322 can provide stability to the post 332 as the post 332translates there through. The adjustment device 336 and the post 332 canform a rack and pinion system as described herein.

The post 332 can span between the tibial system 312 and the femoralsystem 352. The post 332 can be coupled to the post mount 366 of thefemoral system 352. The post mount 366 can be located on one side of themounting block 322 and the post 332 can extend through the opposite sideof the mounting block 322. The movement of the post 332 can causecorresponding movement of the femoral system 352 relative to the tibialsystem 312. The translation of the post 332 can cause correspondingtranslation of the femoral system 352 relative to the tibial system 312.

During distraction, the post 332 is translated within the guide portion330 of the mounting block, 322. See FIG. 4A. As the post 332 is moved,the femoral system 354 moves as well. The post 332 can cause translationof the post mount 366 coupled thereto. The post mount 366 can causetranslation of the extension member 360 and the femoral baseplate 354.The femoral system 352 translates as a unit with the post 332.

By translation of the post 332, the femoral baseplate 354 can be movedrelative to the tibial baseplate 314 to increase or decrease a gap therebetween. The femoral baseplate 354 can be moved away from the tibialbaseplate 314 (e.g. in a proximal direction). The femoral baseplate 354can be moved towards the tibial baseplate 314 (e.g. in distaldirection). The femoral baseplate 354 can be moved to increase the gapbetween the tibia and the femur.

For example, the femoral baseplate 354 can be moved in a verticallyupwards (e.g. proximal) direction to apply pressure to the distalcondyles of a femur or other bony structure in the body. The femoralbaseplate 354 can move the condyles of the femur to a desired position.This movement can distract the knee joint, surrounding soft tissue,and/or ligaments. In some embodiments, a pressure or force gauge orgauges can be incorporated in the system 310 to determine the amount ofcompressive force which is applied by femoral baseplate 354 against thecondyles of the femur.

In some embodiments, the femoral baseplate 354 can be rotationallycoupled to the post mount 366. The femoral baseplate 354 can adjustrelative to the patient's anatomy. For example, the femoral baseplate354 can rotate relative to the plane containing the tibial baseplate314. In a preferred arrangement, the femoral baseplate 354 can rotate inone or more directions about the post mount 366. This rotation canfacilitate use of the system 310 in knee joints which vary in size, andwhere for example the femoral condyles in a particular knee joint arespaced significantly far apart. This rotation can also allow the femoralbaseplate 354 to be inserted through a relatively narrow incision in thebody and then rotate once inside the knee joint to engage the femoralcondyles.

Referring to FIG. 9B, the system 310 can include the marking 340 whichindicates the distance the post 332 has moved. In some embodiments, themarking 340 is a scale which is visible to the user. In someembodiments, the marking 340 is captured by the camera 344. The post322, or a portion thereof, that extends beyond the mounting block 322can include the marking 340. The marking 340 can align with the camera344 of the reference sensor device 16. The camera 344 can capture animage of the marking 340. The marking 340 can be a distraction distancebetween the tibial baseplate 314 and the femoral baseplate 354.

In some embodiments, when the system 310 is being used to distract theknee joint, a ligament or ligaments can be released on either or bothsides of the knee. The user can modify the ligament(s) of the knee toprovide a desired balance of forces around the knee joint.

Referring to FIGS. 9A and 9C, the system 310 can include a drill guide380 for one or more femoral cuts. In some methods of use, the user canmake femoral cuts after distraction. As described herein, the drillguide 380 can be a modular device that can be coupled or decoupled fromthe mounting features 370, which are shown in FIG. 9C. In someembodiments, the drill guide 380 can be stabilized relative to thetibial baseplate 314. The drill guide 380 can be parallel to the tibialbaseplate 314. In some embodiments, the drill guide 380 allows the userto place one or more pins that can aid in mounting a cutting blockconfigured to make one or more cuts in the femur at an angle selectedrelative to (e.g., parallel to) the tibial baseplate 314.

FIG. 10 is an embodiment of a system 410. The system 410 can include anyof the features of the system 310 described herein. The system 410 caninclude a tibial system 412, a tibial baseplate 414, a mounting block422, a first coupler 424, an additional coupler 426, a post 432, a rack434, an adjustment device 436, an interface 438, a femoral system 452, afemoral baseplate 454, a catch 458, a post mount 466, a second coupler474, as shown in FIG. 10 . FIG. 10 also shows the system 410 in use witha knee in extension. The system 310 can be used when the knee is inextension, as described herein. The catch 458 is shown with a knob. Theuser can rotate the knob to limit the movement of the post 432.

4. Distraction in Extension

During a knee joint replacement procedure, the system 310 describedabove can be used to align and balance the ligamentous structure of theknee joint and/or determine an orientation for a cut or cuts along thefemur. The system 410 could be used as well, but for compact descriptionthe discussion distraction in extension will be presented in connectionwith the system 310.

In some methods of use, the proximal (i.e. upper) tibia can be cut. Insome methods of use, the tibia is resected prior to using the system 310and/or prior to resecting the femur. For example, and as describedabove, a tibial preparation system 210 or other tibial preparationsystem can be used to resect a portion or portions of the tibia, suchthat the proximal end of the tibia comprises generally a flat plane orplateau. Based on pre-operative determinations of desired varus/valgus,posterior/anterior, and/or other angles for this tibial resection plane,the plateau can be perpendicular to the mechanical axis, or at an angleother than perpendicular to the mechanical axis.

In some methods of use, the femur can be cut. In some methods of use,the femur is resected prior to using the system 310. For example, and asdescribed above, a femoral preparation system 10 or other femurpreparation system can be used to resect a portion or portions of thefemur, such that the distal end of the femur comprises generally a flatplane. Based on pre-operative determinations of desired varus/valgus,posterior/anterior, and/or other angles for this femur resection plane,the resection can be perpendicular to the mechanical axis, or at anangle other than perpendicular to the mechanical axis. In sometechniques, this cut is referred to as the distal femoral cut (DFC). TheDFC removes a distal (i.e., lower) portion of the femur.

In some methods of use, the leg is positioned in full extension (notshown). The tibial baseplate 314 and the femoral baseplate 354 can beinserted into the knee joint. The tibial baseplate 314 can be positionedon the tibial plateau. The femoral baseplate 354 can be positioned abovethe tibial plateau. In some embodiments, the femoral baseplate 354 ispositioned underneath the femoral resection. In some embodiments, thefemoral baseplate 354 is positioned underneath the femoral condyles.Once the tibial baseplate 314 and the femoral baseplate 354 are insertedinto the knee joint, the femoral baseplate 354 can be moved by turningthe adjustment devices 336. For example, the femoral baseplate 354 canbe moved away from the tibial baseplate 314. In some embodiments, thefemoral baseplate 354 moves into contact with distal aspects of thefemoral condyles. In some embodiments, the femoral baseplate 354 movesinto contact with resected femur. The movement causes the system 310 toapply an opposing force or forces to the proximal tibia and the distalfemur. This force can distract the knee joint and the surrounding softtissue and/or ligaments. The femoral baseplate 354 can apply a differentamount of pressure or force to each femoral condyle. The femoralbaseplate 354 can apply the same amount of pressure or force to eachfemoral condyle. In some methods of use, the femoral baseplate 354 canrotate to provide equal force or pressure to each femoral condyle. Insome embodiments, the tibial baseplate 314 can remain stationary whilethe femoral baseplate 354 is translated and/or rotated.

In some methods of use, the user can distract the knee joint. The usercan apply a force until the femur is held in tension. The user can havea visual indication of the gap as the gap increases. In some methods ofuse, the user can also have a visual indication that a gap, or distance,between one femoral condyle and the tibial plateau is substantiallyidentical to the gap, or distance, between the other femoral condyle andthe tibial resection. In some methods of use, the user can also have avisual indication that a gap, or distance, between the femoral resectionand the tibial resection is substantially rectangular. In some methodsof use, the user can also have a visual indication that the femoralresection is parallel to the tibial resection.

In some embodiments, the user can release one or more ligaments in theknee joint prior to or during the knee distraction in order tofacilitate simultaneous symmetry of the gaps, mechanical axis alignment,and/or balancing of the soft tissue and/or ligaments in the knee joint.In some methods of use, the user can modify the soft tissue to align thefemoral baseplate 354 and the tibial baseplate 314. The user can nick orcut soft tissue to adjust for laxity of the knee joint. The userperforms soft tissue balancing until the femoral baseplate 354 and thetibial baseplate 314 are parallel or approximately parallel. The usercan release ligaments when the knee is in extension based on the angleoutput of the surgical orientation device 14. In some embodiments, theuser releases soft tissue until the angle measurement is zero. The zeroangle measurement indicates that the femoral baseplate 354 is parallelto the tibial baseplate 314.

The surgical orientation device 14 and/or the reference device 16 can beconfigured to measure rotation which is related to the relative tensionin the medial and lateral soft tissue on the medial and/or lateral sidesof the knee joint. In some embodiments, the adjustment device 336 iscalibrated such rotation of the interface 338 corresponds to a resultingforce. For example, each rotation can correspond to a pre-determinedamount of force or pressure on the femoral baseplate 354. In someembodiments, the system 310 can calculate the force from the distractiondistance. In some embodiments, the system 310 can calculate the forcefrom the area of the femoral baseplate 354 and/or the tibial baseplate314. In some embodiments, the system 310 can comprise sensors, or otherstructures, which can relay information to the surgical orientationdevice 14 and/or the reference sensor device 16 about the degree offorce being exerted upon the femoral baseplate 354. In some embodiments,the system 310 can comprise sensors, or other structures, which canrelay information to the surgical orientation device 14 and/or thereference sensor device 16 about the degree of force being exerted uponthe tibial baseplate 314.

The surgical orientation device 14 can be configured to display thefemur rotation. The femur rotation is detected by the surgicalorientation device 14 when the soft tissue is tensioned. The surgicalorientation device 14 can be configured to display the rotation of thefemoral baseplate 354 relative to the tibia baseplate 314 when the kneeis tensioned. The surgical orientation device 14 can display thisinformation, for example, on the visual display located within thesurgical field. If the tension, pressure and/or force applied to thesoft tissue is too great, the user can change the tension by adjusting(e.g. turning) one or more of the adjustment members 336.

The surgical orientation device 14 and/or the reference device 16 can beconfigured to measure the distraction distance between the femoralbaseplate 354 and the tibial baseplate 314. As described herein, thecamera 344 can capture an image corresponding to the distractiondistance. The camera 344 can capture an image of the marking 340. Theimage can correspond with a distance translated by the post 332 duringdistraction. The distance changes as the post 332 slides throughmounting block 322. While the femoral baseplate 354 is being movedand/or rotationally adjusted, and the knee joint is being distracted,the camera 344 can capture an image corresponding to the distractiondistance. The image can correspond to the distraction distance betweenthe femoral baseplate 354 and the tibial baseplate 314.

In some methods, the surgical orientation device 14 and/or the referencedevice 16 converts the image of the camera 344 into a distractiondistance. In some methods, the surgical orientation device 14 and/or thereference device 16 converts the image of the camera 344 into anextension measurement of the post 332. In some embodiments, the surgeonwill enter an input (e.g., depress a button, interact with user input28) to collect data from the reference device 16. In some methods, thesurgeon will enter an input (e.g., depress a button) to collect datafrom the camera 344. In some embodiments, the surgeon will enter aninput (e.g., depress a button) to collect data from the reference device16 and the camera 344 simultaneously. In some methods, the referencedevice 16 and/or the camera 344 will only send data to the surgicalorientation device 14 if the reference device 16 is stable ornon-moving.

The surgical orientation device 14 can be configured to displayinformation during distraction. The surgical orientation device 14 candisplay information in real-time. The surgical orientation device 14 candisplay information as data from the reference device 16 and/or thecamera 344 is acquired. The surgical orientation device 14 can displaythe distraction distance of the femur and the tibia. The information canbe a measured distance (e.g., 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm,8 mm, 9 mm, 10 mm, etc.). The information can be any visual indicator(e.g., a bullseye, target, or sliding scale). The surgical orientationdevice 14 can display this information, for example, on the display 26located within the surgical field.

The surgical orientation device 14 and/or the reference sensor device 16can store any data related to the distraction. The surgical orientationdevice 14 and/or the reference sensor device 16 can be configured tostore the distraction distance of the femur and the tibia when the legis in extension. The surgical orientation device 14 and/or the referencesensor device 16 can be configured to store the extension gap when theleg is in extension. The surgical orientation device 14 and/or thereference sensor device 16 can store the distraction distance inextension for a later comparison to the leg in flexion. The surgicalorientation device 14 and/or the reference sensor device 16 can storethe distraction distance for post-operative use.

In some methods of use, the femur is resected prior to placing the legin extension. The system 310 can measure angles relative to the tibiaresection. In some methods of use, the femur is resected using thefemoral preparation system 10 described herein. The femoral preparationsystem 10 can position a cutting block at a specific angle relative tothe mechanical axis of the femur.

5. Distraction in Flexion

In some knee joint procedures, another cut which can be made is aposterior femoral cut (PFC). In preparation for the posterior femoralcut, the leg can be placed in approximately 90 degrees of flexion asshown in FIG. 11A. FIG. 11A shows the leg in flexion, with the tibialbaseplate 314 and the femoral baseplate 354 inside the knee joint.

In some methods of use, the proximal (i.e. upper) tibia can be cut asshown in FIG. 11A. The tibial preparation system 210 or other tibialpreparation system can be used to resect a portion or portions of thetibia, such that the proximal end of the tibia comprises generally aflat plane or plateau. In some methods of use, the femur can be cut asshown in FIG. 11A. In some embodiments, femoral preparation system 10 orother femur preparation system can be used to resect a portion orportions of the femur, such that the proximal end of the femur comprisesgenerally a flat plane or plateau. In some embodiments, the femur isresected after distraction in extension.

In some methods of use, after completing the tibial resection and thedistal femoral resection, the user flexes the knee to 90 degrees andinserts the system 310. In some methods of use, the leg is positioned inflexion. The tibial baseplate 314 and the femoral baseplate 354 can beinserted into the knee joint. The tibial baseplate 314 can be positionedon the tibial plateau. The femoral baseplate 354 can be positioned abovethe tibial plateau. In some embodiments, the femoral baseplate 354 ispositioned underneath the femoral condyles as shown in FIG. 11A.

Once the tibial baseplate 314 and the femoral baseplate 354 are insertedinto the knee joint, the femoral baseplate 354 can be moved by turningthe adjustment device 336. As described herein, the adjustment device336 can be rotated to move the femoral baseplate 354 away from thetibial baseplate 314, thereby distracting the knee joint. The adjustmentdevices 336 can cause translation of the post 332. The post 332 can becoupled to the femoral baseplate 354, such that translation of the post322 causes translation of the femoral baseplate 354. The femoralbaseplate 354 can be moved away from the tibial baseplate 314 as shownin FIG. 11A. In some embodiments, the femoral baseplate 354 moves intocontact with posterior aspects of the femoral condyles. The movementcauses the system 310 to apply an opposing force or forces to theproximal tibia and the distal femur. This force can distract the kneejoint and the surrounding soft tissue and/or ligaments. The system 310can apply individual opposing force or forces to the tibial plateau andthe femoral condyles. Each condyle can be distracted individually,simultaneously, and/or consecutively.

In some embodiments, the femoral baseplate 354 can rotate as shown inFIG. 11B. The femoral baseplate 354 can rotate as the post 332translates. The femoral system 352 can include the post 332 describedherein. The femoral system 352 can include a post mount 366 coupled tothe post 322. In some embodiments, the post mount 366 and the post 332form a unitary structure. The translation of the post 332 can causecorresponding translation of the post mount 366 as described herein. Thepost mount 366 can allow rotation of the femoral baseplate 354 relativeto the post 322. The femoral system 352 can include a rotationalinterface 368, not shown in FIG. 11B. The rotational interface 368 canbe a pin. The femoral baseplate 354 can rotate about the rotationalinterface 368 relative to the post 322. The femoral baseplate 354 canrotate about the rotational interface 368 relative to the tibialbaseplate 314.

The femoral baseplate 354 can apply a different amount of pressure orforce to each femoral condyle. The femoral baseplate 354 can apply thesame amount of pressure or force to each femoral condyle. The femoralbaseplate 354 can rotate in order to put both femoral condyles intension. The post 332 can be translated until both femoral condyles areunder tension by the system 310. The post 332 can be translated untilboth femoral condyles experience a predetermined force. The adjustmentdevice 336 can be rotated to distract the joint. The adjustment device336 can be rotated until both collateral ligaments are under tension. Insome embodiments, the tibial baseplate 314 can remain stationary whilethe femoral baseplate 354 is rotated.

FIG. 11B illustrates the additional coupler 326 and the second coupler374. FIG. 11C illustrates the surgical orientation device 14 and thereference sensor device 16 coupled to the system 310. As describedherein, the mounting block 322 can include one or more additionalcouplers 326. The additional coupler 326 can be configured to couplewith the reference sensor device 16. The one or more additional couplers326 can be positioned on any surface of the mounting block 322. Theadditional coupler 326 can be positioned such that the longitudinal axisof the reference sensor device 16 is perpendicular to the longitudinalaxis of the tibia. The additional coupler 326 can be positioned suchthat the longitudinal axis of the reference sensor device 16 isperpendicular to the mechanical axis.

The femoral system 352 can include a second coupler 374. The secondcoupler 374 can be configured to couple with the surgical orientationdevice 14. The second coupler 374 can be positioned such that thelongitudinal axis of the surgical orientation device 14 aligns with thelongitudinal axis of the tibia. The second coupler 374 can be positionedsuch that the longitudinal axis of the surgical orientation device 14aligns with the mechanical axis.

FIG. 11C illustrates the surgical orientation device 14 and thereference sensor device 16. The surgical orientation device 14 can becoupled to the second coupler 374. The reference sensor device 16 can becoupled to the additional coupler 326. As described herein, the surgicalorientation device 14 is rotationally coupled to the femoral baseplate354. As the femoral baseplate 354 rotates, the surgical orientationdevice 14 can rotate as well.

As described herein, the reference sensor device 16 can measure thedistraction distance. The reference sensor device 16 can include thecamera 344. The camera 344 can provide a measurement of distraction whenthen leg is in extension. The camera 344 can provide an indication ofthe extension of the post 332. For example, while the femoral baseplate354 is being moved and/or rotationally adjusted, and the knee joint isbeing distracted, the camera 344 can provide a distance measurement. Thedistance measurement can correspond to the distraction distance betweenthe femoral baseplate 354 and the tibial baseplate 314. In someembodiments, the camera 344 can capture an image of the marking 340,described herein. In some embodiments, the camera 344 can read marking340, such as a machine readable marking. The surgical orientation device14 can be configured to display the flexion gap. In some methods of use,the user can read the display 24 of the surgical orientation device 14.In some methods of use, the user can read the markings 340. The system310 can calculate the anterior-posterior shift needed to match flexionand extension gaps. In some embodiments, the user can compare twonumbers shown on the display 24 of the surgical orientation device 14.In some embodiments, the display can show the difference in gaps.

The surgical orientation device 14 can be configured to displaydistraction distance, as described herein. The surgical orientationdevice 14 can provide a visual indication of the gap as the gapincreases. The surgical orientation device 14 and/or the referencesensor device 16 can convert the image of the camera 344 into a distancemeasurement. The user can refer to the display 26 of the surgicalorientation device 14 for the distraction distance. The distractiondistance can be displayed in real-time. The user can read thedistraction distance on the display 26 of the surgical orientationdevice 14.

The surgical orientation device 14 can be configured to display therotation angle of the surgical orientation device 14 relative to thetibial baseplate 314. The rotation angle of the surgical orientationdevice 14 can correspond to the posterior condyle angle. The display 26can indicate the angle of rotation of the femoral baseplate 354. Theuser can read the rotation angle on the display 26 of the surgicalorientation device 14. In some methods of use, the surgical orientationdevice 14 can provide a visual indication whether a rotation angle iswithin a pre-determined range. In some methods of use, the surgicalorientation device 14 can provide a visual indication of the femurrotation. In some methods of use, the surgical orientation device 14 canprovide a visual indication of the soft-tissue balancing. In somemethods of use, the surgical orientation device 14 can provide a visualindication that the femur condyles are angled relative to the tibialplateau. The display 26 can provide a digital readout of the rotationangle.

The surgical orientation device 14 and/or the reference sensor device 16can record the angle of rotation. The surgical orientation device 14and/or the reference sensor device 16 can store the angle of rotation.The surgical orientation device 14 can provide an angle reading inreal-time. The rotation angle of the surgical orientation device 14 cancorrespond to the posterior condyle angle. The rotation angle of thesurgical orientation device 14 can correspond to the posterior condyleangle input to a drill guide or cutting guide. The user can set theangle of a cutting block 394 or drill guide 380 based on the rotationangle displayed on the surgical orientation device 14. The cutting block394 or drill guide 380 provided with the implant can be adjustable basedon the posterior condyle angle. The system 310 provides an accuratereading of the posterior condyle angle.

In some methods of use, the surgical orientation device 14 can provide avisual indication of the medial distraction distance. In some methods ofuse, the surgical orientation device 14 can provide a visual indicationof the lateral distraction distance. In some methods of use, thesurgical orientation device 14 and/or the reference sensor device cancalculate the medial/lateral distraction distance based on the rotationangle of the surgical orientation device 14. In some methods of use, thesurgical orientation device 14 and/or the reference sensor device cancalculate the medial/lateral distraction distance based on thedistraction distance. In some methods of use, the surgical orientationdevice 14 and/or the reference sensor device can calculate themedial/lateral distraction distance based on the parameters of thefemoral baseplate 354. In some methods of use, the surgical orientationdevice 14 can provide a visual indication of the difference in a gap, ordistance, between one femoral condyle and the tibial plateau issubstantially identical to the gap, or distance, between the otherfemoral condyle and the tibial plateau. In some methods of use, thesurgical orientation device 14 can provide a visual indication ofrotation angle. In some methods of use, the surgical orientation device14 can provide a visual indication of distraction distance. In somemethods of use, the surgical orientation device 14 can provide a visualindication of baseplate parameters. In some methods of use, the surgicalorientation device 14 can provide a visual indication of medial andlateral distraction distances. In some methods of use, the distractiondistance is an input to the system 310. In some methods of use, one ormore parameters of the tibial baseplate 314 is an input to the system310. In some methods of use, one or more parameters of the femoralbaseplate 354 is an input to the system 310. In some methods of use, thecondylar width of the femur is an input to the system 310. In somemethods of use, the surgical orientation device 14 can provide a visualindication of a measurement of the condylar width of the femur itself.The measurement of the condylar width can be useful in calculating themedial and lateral distraction distances. In some methods of use, thesurgical orientation device 14 can provide a visual indication that agap, or distance, between the femoral posterior condyles and the tibialplateau is angled. In some methods of use, the surgical orientationdevice 14 can provide a visual indication that the femoral posteriorcondyles is angled relative to the tibial plateau. In some methods ofuse, the surgical orientation device 14 can provide a visual indicationthat the femoral posterior resection is angled relative to the tibialplateau, once it is executed. The visual indication of the posteriorcondyles could be a useful final check after the cut is made. The visualindication of the femoral posterior resection could be a useful finalcheck after the cut is made.

In some methods of use, the surgical orientation device 14 can provide avisual indication of a comparison between the distraction distance inflexion and the distraction distance in extension. The display 26 canprovide a digital readout of the distraction distance. The user canvisually confirm the digital readout of the distraction distance withone or more additional markings 340, such as scale visible to the user.The display 26 can provide a digital readout of the comparison indistraction distance.

In some methods of use, the user can mount drill guide 380 and drillholes with the appropriate anterior-posterior shift based on theanterior-posterior shift calculated by the surgical orientation device14. The anterior-posterior shift can be difference between the gap inextension and flexion. The user can use selected openings 382 in thedrill guide 380 based on the comparison in distraction distance betweenflexion and extension. For instance, if the difference is 2 mm betweenthe distraction distance in flexion and extension, the user can select adifferent parallel row of openings, for instance one that increases ordecreases the height of the cutting plane of the cutting block by 2 mm.For instance, if the difference is 4 mm between the distraction distancein flexion and extension, the user can select a different parallel rowof openings, for instance one that increases or decreases the height ofthe cutting plane of the cutting block by 4 mm. In some embodiments, theuser matches the gap in flexion with the gap in extension. In someembodiments, the user is unable to match the distraction gap in flexionwith the distraction gap in extension, for instance due to constraintson the anatomy. The system 310 can calculate the difference in the gap.The user can select a parallel row of openings 382 in the drill guide382 that correspond to this difference in the gap. The parallel row ofopenings 382 in the drill guide 382 can adjust the femoral cut in adirection parallel to the tibial baseplate 314. The parallel row ofopenings 382 in the drill guide 382 can adjust the femoral cut so thatthe gaps in flexion and extension can match. The user can mount theimplant sizing/drill guide on the distal resection surface of the femur.The user can select the appropriate 4-in-1 cutting block 394. The usercan remove the implant sizing/drill guide. The user can mount the 4-in-1cutting block 394. The user can complete resections. The 4-in-1 cuttingblock 394 will be located with posterior resection slot parallel totibial resection by correct alignment of drilled guide holes.

In some, alternative methods, the user can measure posterior condyleangle on surgical orientation device 14. The posterior condyle angle canbe determined from accelerometer measurements. The user can mount theimplant sizing/drill guide on the distal resection surface of the femur.The user can set the implant sizing/drill guide to this angle. Thesurgical orientation device 14 provides an accurate way to measure theposterior condyle angle. The user can drill holes. The user can selectthe appropriate 4-in-1 cutting block 394. The user can remove theimplant sizing/drill guide. The user can mount the 4-in-1 cutting block394. The user can complete resections. The 4-in-1 cutting block 394 willbe located with posterior resection slot parallel to tibial resection bycorrect alignment of drilled guide holes.

The surgical orientation device 14 and/or the reference sensor device 16can be configured to measure the tension within the soft tissue on themedial and/or lateral sides of the knee joint. In some embodiments, thesurgical orientation device 14 and/or the reference sensor device 16 canbe configured to measure the tension from the distraction distance. Insome embodiments, the system 310 can comprise sensors, or otherstructures, which can relay information to the surgical orientationdevice 14 and/or the reference sensor device 16 about the degree oftensile force being exerted. The surgical orientation device 14 can beconfigured to display the force.

In some embodiments, the user can release one or more ligaments in theknee joint prior to or during the knee distraction in order tofacilitate simultaneous symmetry of the gaps, mechanical axis alignment,and/or balancing of the soft tissue and/or ligaments in the knee joint.In some methods of use, the user can modify the soft tissue to align thefemoral baseplate 354 and the tibial baseplate 314 to alter the angle.The far more common scenario is that soft tissue is modified only inextension. The user can nick or cut soft tissue to adjust for laxity ofthe knee joint. The user performs soft tissue balancing until thefemoral baseplate 354 and the tibial baseplate 314 are at the desiredangle.

The surgical orientation device 14 and/or the reference sensor device 16can store any data related to the distraction. The surgical orientationdevice 14 and/or the reference sensor device 16 can be configured tostore the distraction distance of the femur and the tibia. The surgicalorientation device 14 and/or the reference sensor device 16 can beconfigured to store the distraction distance of the femur and the tibiawhen the leg is in flexion. The surgical orientation device 14 cancompare the distraction distance in flexion and extension. The surgicalorientation device 14 can store data for a post-operative comparison.The surgical orientation device 14 can store data for post-operativerecord of parameters used during the procedure.

After distraction, holes can be drilled into the femur, and referencepins can be inserted. As described herein the drill guide 380 caninclude one or more openings 382. The openings 382 can be used to guidea drill and/or pins. For example, when the system 310 has distracted adistal femur in a knee replacement procedure, a pin or pins can beinserted into the resected surface in order to provide a mountinglocation for a cutting block. The openings 382 can be used as guides forinsertion of these pins.

The openings 382 can be spaced apart from one another in a pattern orpatterns. For example, some of the openings 382 can be spaced slightlyhigher, and/or further away from the tibial baseplate 624 than otheropenings 646. This spacing can be used, for example, to control theorientation of a cutting block which is attached to the pins. Thereference pins can be inserted into various openings 382 of the drillguide 380, again depending on the desired angle of resection. Forexample, and as described above, some of the openings 382 can be locatedat slightly different levels or elevations on the drill guide 380.Depending on where the reference pins are inserted, a slightly differentangle of resection can be achieved (e.g. zero degrees, plus threedegrees, minus three degrees relative to the tibial resection).

FIG. 11D illustrates the use of a sizing guide 390. The system 310 canbe removed as shown in FIG. 11D. The sizing guide can correspond to theselected implant. The sizing guide 390 can be adjusted to the rotationangle displayed on the surgical orientation device 14 during distractionin flexion. The system 310 can set pin locations for the femur cuttingblock. The system 310 can set the rotational alignment for the femurcutting block. The sizing guide 390 is an example of a typicalsizing/drill guide from an implant instrument set. There are othercommercial examples. FIG. 11E is an alternative sizing guide 392. FIG.11F is an embodiment of a 4-in-1 cutting block 394.

Once the reference pins are inserted, a cutting block 394 can be placedonto or coupled with the reference pins. A saw or other cutting devicecan then make appropriate PFC cut or cuts (e.g. an anterior, additionalposterior, and/or chamfer along the femur. Once all of the tibial and/orfemoral cuts are made with the systems and/or methods described above, aknee joint prosthetic or prosthetics can be attached to the distal femurand/or proximal tibia. The knee joint prosthetic devices can comprise areplacement knee joint. The replacement knee joint can be evaluated bythe user to verify that alignment of the prosthetic components in thereplacement knee joint does not create any undesired wear, interference,and/or damage to the patient's anatomy, or to the prosthetic componentsthemselves.

FIG. 12A-12D illustrate additional views of the femoral baseplate 354and the tibial baseplate 314. The femoral baseplate 354 can be rotatedrelative to the tibial baseplate 314. The system 310 can measure theangle of rotation of the femoral baseplate 354 as shown in FIG. 12C. Thesystem 310 can measure the distraction distance of the medial and/orlateral sides of the knee joint as shown in FIG. 12D. FIG. 12E is aschematic illustration of the drill guide 380 comprising openings 382.The drill guide 380 can be coupled to the tibial baseplate 314 asdescribed herein. The drill guide 380 can remain parallel to the tibialbaseplate 314 during rotation of the femoral baseplate 354.

C. Alternative Femoral Preparation and Knee Distraction System

FIGS. 13A-13E show an embodiment of a system 510. The system 510 can beused to perform many functions, as described herein. The system 510 caninclude any of the features of any other system described hereinincluding system 310. The system 510 can be configured to distract theknee joint during a knee replacement procedure. The system 510 can beconfigured to measure the rotation of the femur relative to the tibialresection. The system 510 can be configured to orient a resection plane.The system 510 can be configured to guide posterior resection. Thesystem 510 can be used to prepare the femur, such as facilitate theposterior femoral cut. The system 510 can be configured to provideinformation about how to resect the femur.

The system 510 can comprise the surgical orientation device 14 and thereference sensor device 16 as described herein. The system 510 canfurther comprise one or both of a tibial system 512 and a femoral system552, as described herein. While the tibial system 512 and the femoralsystem 552 are described as discrete subsystems, the system 510 can beconsidered one instrument. In some embodiments, the system 510 can beimplanted as an inseparable assembly. In some embodiments, the discretesubsystems of the system 510 can be positioned on or in the patientseparately. In some embodiments, the discrete subsystems of the system510 can be positioned on or in the patient simultaneously. FIG. 13Eshows additional features as described herein.

1. Tibial System

FIGS. 14A and 14B illustrate the tibial system 512. The tibial system512 can include any of the features of the tibial system 312. The tibialsystem 512 can include a tibial baseplate 514. The tibial baseplate 514can comprise a first surface 518 configured to align with the flatsurface of the resected tibia. The tibial baseplate 514 can include asecond surface 516, opposite the first surface 518 positioned toward thefemur. The tibial system 512 can include an extension member 520. Thetibial system 512 can include a mounting block 522. The extension member520 can span between the mounting block 522 and the tibial baseplate514. The extension member 520 can position the mounting block 522 awayfrom, e.g., anteriorly of, the knee joint.

The mounting block 522 can include a first coupler 524. The firstcoupler 524 can be configured to couple with the surgical ordinationdevice 14 and/or the reference sensor device 16. The first coupler 524can include any of the features of the couplers described herein. In theillustrated embodiment, the first coupler 524 is positioned on a bottomsurface of the mounting block 522. In the illustrated embodiment, thefirst coupler 524 extends perpendicular to the tibial resection. In theillustrated embodiment, the first coupler 524 is positioned such thatthe longitudinal axis of the reference sensor device 16 aligns with thelongitudinal axis of the tibia. The axis of the tibia can beperpendicular to the tibial resection. In the illustrated embodiment,the first coupler 524 is positioned such that the longitudinal axis ofthe reference sensor device 16 aligns with a mechanical axis associatedwith the knee joint, e.g., of the tibia or the leg. In some embodiments,the mounting block 522 can include one or more additional or alternativecouplers as described herein.

The mounting block 522 can include a guide portion 530. The guideportion 530 can extend entirely through the mounting block 522 or aportion thereof. The guide portion 530 can include at least an openingon the bottom of the mounting block 522. In some embodiments, the guideportion 530 can include an opening on the bottom of the mounting block522 and on the top of the mounting block. The guide portion 530 caninclude at least two diametrically opposed openings. In someembodiments, the guide portion 530 can be a channel through the mountingblock 522. In some embodiments, the guide portion 530 can include around or circular channel through the mounting block 522. Otherconfigurations for the guide portion 530 are contemplated including atriangular, elliptical, rectangular, or polygonal channel.

The mounting block 522 can be configured to facilitate movement of apost 532 of the femoral system 552 therethrough. The post 532 and theguide portion 530 can a have complementary or correspondingcross-sectional profile. The post 532 and the guide portion 530 can havecorresponding cross-sectional dimension or diameter. In someembodiments, the guide portion 530 and the post 532 are substantiallysimilar in cross-sectional dimensions. The post 532 and the guideportion 530 can be shaped to allow metered movement of the post 532through the guide portion 530. The guide portion 530 can guide the post532 through the mounting block 522. The guide portion 530 can beconfigured to allow the post 532 to slide through the mounting block522. As described herein, the post 532 can be coupled to the femoralsystem 552. The post 532 can be a portion of an actuation system thatprovides for movement of the femoral system 552 relative to the tibialsystem 512.

In some embodiments, a portion of the post 532 and the guide portion arerounded. An advantage of a rounded or circular post 532, or a rounded orcircular portion thereof, can include tighter tolerances between themounting block 522 of the tibial system 512 and the post 532 of thefemoral system 552. An advantage can include better alignment betweenthe tibial system 512 and the femoral system 552. An advantage caninclude more precision in aligning a scale or marking located on thepost 532 with the camera 334 of the reference sensor device 16. Anadvantage can include higher precision movement between the tibialsystem 512 and the femoral system 552. An advantage can includereduction or prevention of unwanted movement, for example, side to sidemovement between the tibial system 512 and the femoral system 552. Anadvantage can include reduced manufacturing costs associated withmanufacturing the rounded guide portion 530 and the rounded post 532.

FIG. 14B illustrates the post 532 relative to the mounting block 522 inone position. The post 532 can include a marking 540 which can extendbelow the mounting block 522. The post 532 can include a rack 534 whichcan extend below the mounting block 522 in the illustrated position. Thepost 532 can extend from below the mounting block 522 to above themounting block 522. The post 532 can connect to the femoral system 552as described herein. The marking 540 can be optically detected by thecamera 344. The marking 540 can be any camera-readable representation.

In some embodiments, the guide portion 530 can include an anti-rotationconfiguration limit rotation, e.g., to allow the post 532 to extend inonly one orientation through the guide portion 530 of the mounting block522. In some embodiments, components of the actuation system allow thepost 532 to extend in only one orientation through the guide portion 530of the mounting block 522. The post 532 and/or the guide portion 530 caninclude a feature to reduce or prevent rotation. In some embodiments,the shape of the post 532 can reduce or prevent rotation.

FIGS. 15A-15D illustrates the actuation system of the system 510. FIG.15E is a perspective view of the post 532. The system 510 can includethe actuation system to allow movement between the tibial system 512 andthe femoral system 552. The actuation system can be positioned anywherewithin the system 510. In the illustrated embodiment, the tibial system512 can house certain components of the actuation system. The actuationsystem can include the post 532. The post 532 can connect the tibialsystem 512 and the femoral system 552.

The actuation system can include an adjustment device 536. Theadjustment device 536 can be located at least partially within themounting block 522. The adjustment device 536 can extend from themounting block 522 to allow movement of the adjustment device 536 by theuser. FIG. 14B illustrates one positional relationship between theadjustment device 536 and the mounting block 522.

The adjustment device 536 can be configured to provide a force ofdistraction between the tibial system 512 and the femoral system 552.The adjustment device 536 can be configured to maintain the positionbetween the tibial system 512 and the femoral system 552. The adjustmentdevice 536 can be configured to maintain the position of the post 532relative to the mounting block 522. The adjustment device 536 can beconfigured to apply a force in the range of 150 N to 200 N. Theadjustment device 536 can be configured to apply 50 N, 60 N, 70 N, 80 N,90 N, 100 N, 110 N, 120 N, 130 N, 140 N, 150 N, 160 N, 170 N, 180 N, 190N, 200 N, 210 N, 220 N, 230 N, 240 N, 250 N, 260 N, 270 N, 280 N, 290 N,300 N, or any range including two or more of the foregoing values. Theadjustment device 536 can be configured to translate the post 532relative to the mounting block 522 upon actuation by the user.

In some embodiments, the adjustment device 536 can include a pinionconfigured to interact with a rack 534 on the post 532. In someembodiments, the adjustment device 536 can include a drive pinion. Thepost 532 can be substantially straight along its length. The rack 534can extend along an edge of the post 532. The rack 534 can extend alongthe length of the post 532, or a portion thereof. The adjustment device536 can interact with the rack 534 such that rotation of the adjustmentdevice 536 causes translation of the post 532. The adjustment device 536can be free to rotate within the mounting block 522. The adjustmentdevice 536 can be prevented from translation within the mounting block522. Other configurations are contemplated. The adjustment device 536can include any feature to allow relative movement including a gear,detent, pawl, pinion, screw, ramp, rack, etc. The post 532 can includeany corresponding feature to allow relative movement including a gear,detent, pawl, pinion, screw, ramp, rack, etc. The adjustment device 536can include any mechanical feature which can be actuated to causetranslation of the post 532.

In some embodiments, the adjustment device 536 can be rotated to causetranslational movement of the post 532. In some embodiments, theadjustment device 536 can be translated to cause translational movementof the post 532. The adjustment device 536 can include an interface 538which can engage a driver. The interface 538 can allow the user torotate or translate the adjustment device 536. The interface 538 caninclude a recess or a protrusion. In some embodiments, the interface 538can be a hex recess. The interface 538 can allow rotation of theadjustment device 536 by a driver as described herein. Otherconfigurations of the interface 538 are contemplated.

The actuation system can include a catch 548. The catch 548 can belocated at least partially within the mounting block 522. In someembodiments, the catch 548 can extend from the mounting block 522 toallow adjustment of the catch 548 by the user. In some embodiments, thecatch 548 can be contained within the mounting block 522 such that thecatch 548 is inaccessible to the user. FIG. 14B illustrates onepositional relationship between the catch 548 and the mounting block522.

The catch 548 can be configured to provide incremental positioningbetween the tibial system 512 and the femoral system 552. The catch 548can be configured to provide fine resolution positioning of the post 532relative to the mounting block 522. The catch 548 can be configured toallow positioning at increments of 1 mm. The catch 548 can be configuredto allow positioning at increments of 0.25 mm, 0.5 mm, 0.75 mm, 1 mm,1.25 mm, 1.5 mm, 1.75 mm, 2 mm, or any range including two or more ofthe foregoing values. The catch 548 can be configured to allowadjustment of the position of post 532 relative to the mounting block522.

In some embodiments, the catch 548 can be a pawl configured to interactwith a ratchet 550 on the post 532. In the illustrated embodiment, thecatch 548 is a spring loaded pawl. In some embodiments, the catch 548can be biased into engagement with the ratchet 550. The post 532 can besubstantially straight along its length. The ratchet 550 can extendalong an edge of the post 532. The ratchet 550 can extend along thelength of the post 532, or a portion thereof. The catch 548 can interactwith the ratchet 550 such that actuation of the catch 548 can causeincremental positional changes of the post 532. The catch 548 can befree to actuate within the mounting block 522. The catch 548 can beprevented from translation within the mounting block 522. Otherconfigurations are contemplated. The catch 548 can include any featureto allow relative movement including a gear, detent, pawl, pinion,screw, ramp, rack, etc. The post 532 can include any correspondingfeature to allow relative movement including a gear, detent, pawl,pinion, screw, ramp, rack, etc. The catch 548 can include any mechanicalfeature which can be actuated to cause translation of the post 532. Insome embodiments, the catch 548 can allow unidirectional movement of thepost 532. In some embodiments, the catch 548 can allow bidirectionalmovement of the post 532.

The catch 548 can interact with the ratchet 550 such that translation ofthe post 532 can be maintained at an incremental position. As the useractuates the adjustment device 536, the catch 548 can be configured toslide along the teeth of the ratchet 550. When the user stops actuatingthe adjustment device 536, the catch 548 can maintain the position ofthe post 532. An advantage of the catch 548 can be to allow fineradjustments of the post 532 than the adjustment device 536. In someembodiments, the gears or teeth of the ratchet 550 can be at smallerincrements than the gears or teeth of the rack 534. An advantage of thecatch 548 can be to prevent slippage of the adjustment device 536 oncethe user stops actuating the adjustment device 536. Without the catch548, a gear of the adjustment device 536 may be able to slip thedistance between engaging a bottom surface of a gear on the rack 534 toengaging a top surface of an adjacent gear on the rack 534. An advantageof the catch 548 can be to limit movement in one or more direction. Insome embodiments, when the catch 548 is engaged with the ratchet 550,the translation of the post 532 can be limited in one direction. In someembodiments, when the catch 548 is engaged with the ratchet 550, thetranslation of the post 532 can be limited in both directions. Thecontact between the catch 548 and the ratchet 550 can additionally oralternatively provide a force (e.g. frictional) which can hold the post532 in a desired position, until the adjustment device 536 is turnedagain.

In some embodiments, the catch 548 can automatically engage the ratchet550 regardless of movement of the adjustment device 536. In someembodiments, the catch 548 is spring loaded or biased into engagementwith the ratchet 550. In some embodiments, the catch 548 can be biasedto slide along the ratchet 550 when the adjustment device 536 is beingactuated. In some embodiments, the catch 548 can be biased to maintainits position along the ratchet 550 when the adjustment device 536 stopsbeing actuated. In some embodiments, the catch 548 can be controlled bythe user. In some embodiments, the catch 548 can be engaged ordisengaged with the ratchet 550 by the user interacting with aninterface (not shown). In some embodiments, the catch 548 is notaccessible or controllable to the user.

In some embodiments, the user can experience feedback related tomovement of the post 532 relative to the catch 548. For example, thesystem 510 can provide audible, tactile, and/or visual feedback to theuser, indicating the degree or extent to which the post 532 has beenmoved. In some embodiments, the catch 548 proves audible feedback. Insome embodiments, the catch 548 proves tactile feedback. In someembodiments, the user can hear and/or feel the catch 548 contacting theratchet 550 as the post 532 moves up and/or down. This contact canproduce an audible click, or clicks. In some embodiments, the user canview a scale or other marking on the post 532 related to the position ofthe catch 548. Other modes of feedback are contemplated.

The actuation system can include the post 532. The post 532 can belocated at least partially within the mounting block 522. In someembodiments, the post 532 can extend from the mounting block 522 toallow translation of the post 532 relative to the mounting block 522.FIG. 14B illustrates one positional relationship between the post 532and the mounting block 522.

The post 532 can include an upper portion 542. In some embodiments, theupper portion 542 can be configured to move within the mounting block522. The upper portion 542 can include the rack 534. The upper portion542 can include the ratchet 550. The upper portion 542 can include arounded cross-sectional shape. The post 532 can include a lower portion546. The lower portion 546 can include any cross-sectional shape,including a non-round cross-sectional shape. In the illustratedembodiment, the lower portion 546 can have a rectangular cross-sectionalshape. The post 532 can include a window 544. The upper portion 542 canbe above the window. The lower portion 546 can include the window 544.

In some embodiments, the post 532 can include one or more markings 540.The marking 540 can be located on the lower portion 546. The lowerportion 546 can include at least one flat side for the marking 540 to bedisposed thereon. The marking 540 can indicate the position of the post532. By taking one or more readings of the marking 540, the system 510can determine the distance traveled by the post 532. In someembodiments, the marking 540 can be a scale. In some embodiments, themarking 540 can be captured by the camera 344. The post 522, or aportion thereof, that extends beyond the mounting block 522 can includethe marking 540. The marking 540 can align with the camera 344 of thereference sensor device 16. The camera 344 can capture an image of themarking 540. The image of the marking 540 can be analyzed to determinean initial position of the tibial system 512 and the femoral system 552.The image of the marking 540 can be captured and analyzed at anothertime during the procedure. The marking 540 can indicate a distractiondistance between the tibial system 512 and the femoral system 552.

FIG. 16A illustrates a moveable interface 600. The moveable interface600 can be configured to slide relative to the mounting block 522. Insome embodiments, the moveable interface 600 can include a surface 602configured to abut the shin of the patient. In some embodiments, thesurface 602 of the moveable interface 600 can be configured to abut ananatomical landmark. In some embodiments, the surface 602 of themoveable interface 600 can include a portion configured to engageanother portion of the anatomy of the patient. The moveable interface600 can include any shape to allow the moveable interface 600 to move orslide relative to the mounting block 522. The moveable interface 600 caninclude one or more sides 604, 606, 608. The moveable interface 600 caninclude two parallel sides 604, 606. The moveable interface 600 caninclude a front side 608 to connect the two parallel sides. The frontside 608 can include the surface 602. The moveable interface 600 caninclude a U-shaped configuration. The moveable interface 600 can haveone or more flat surfaces. In the illustrated embodiments, the moveableinterface 600 can include three flat side surfaces. In the illustratedembodiments, the moveable interface 600 can include three outer surfacesincluding two side outer surfaces and a front outer surface. The frontouter surface can be configured to contact the anatomy of a patient.

In FIG. 16B, the front cover of the mounting block 522 is removed forillustration of the internal contents of the block. The moveableinterface 600 can stabilize the mounting block 522 relative to thetibia. The moveable interface 600 can be located at least partiallywithin the mounting block 522. In some embodiments, the moveableinterface 600 can extend from the mounting block 522 to allowtranslation of the moveable interface 600 relative to the mounting block522. FIG. 16B illustrates one positional relationship between themoveable interface 600 and the mounting block 522. The moveableinterface 600 can be configured to slide within the mounting block 522.

FIG. 16B illustrates a moveable interface lock 610 associated with themoveable interface 600. The moveable interface lock 610 can be locatedat least partially within the mounting block 522. The moveable interfacelock 610 can include a turnbuckle 612 which includes two segments havingopposite threads. Each end of the turnbuckle 612 engages a threaded endof a shoulder screw 614. The shoulder screw 614 can include a head 616and a shaft 618. The head 616 of the shoulder screw 614 can be locatedadjacent to the moveable interface 600. In some embodiments, the shaft618 of the shoulder screw 614 can be inserted through a slot 620 in themoveable interface 600 to engage the turnbuckle 612. The head 616 of theshoulder screw 614 can be located adjacent to an outer surface of themoveable interface 600.

The turnbuckle 612 can include a handle 622 for actuation of theturnbuckle 612 by the user. When the user translates the handle 622, theturnbuckle 612 can rotate. The rotation of the turnbuckle 612 draws eachshoulder screw 614 toward the turnbuckle 612. The rotation of theturnbuckle 612 draws each shoulder screw 614 against the moveableinterface 600. The frictional interference between the shoulder screws614 and the moveable interface 600 can reduce or prevent movement of themoveable interface 600. Other configurations of locking the moveableinterface 600 are contemplated. In some embodiments, only one shoulderscrew 614 can be utilized to lock the moveable interface 600. In someembodiments, only one point of contact can be utilized to lock themoveable interface 600. In some embodiments, two or more points ofcontact can be utilized to lock the moveable interface 600.

In some embodiments, the moveable interface 600 can be configured toslide in a single plane. The moveable interface lock can preventmovement in the plane when the shoulder screws 614 engage the moveableinterface 600. In the illustrated embodiments, two shoulder screws 614are utilized but other configurations are contemplated (e.g., oneshoulder screw, three shoulder screws, four shoulder screws, sixshoulder screws, etc.). In the illustrated embodiments, one shoulderscrew 614 engages each side of the moveable interface 600. As theshoulder screws 614 tighten toward the turnbuckle 612, the shoulderscrews 614 provide a clamping force on the moveable interface 600. Othermechanisms to reduce or prevent sliding of the moveable interface 600are contemplated.

The moveable interface 600 can be translated relative to the mountingblock 522 prior to inserting the tibial baseplate 514. The moveableinterface 600 can limit insertion depth of the tibial baseplate 514. Themoveable interface 600 can be translated relative to the mounting block522 after inserting the tibial baseplate 514. The moveable interface 600can provide a measurement of the depth of insertion of the tibialbaseplate.

The moveable interface 600 can include one or more markings 624. Themarking 624 can indicate length or extension of the moveable interface600. The marking 624 can indicate an insertion depth of the system 510.The marking 624 can indicate an insertion depth of the tibial baseplate514. The marking 624 can include a scale. The marking 624 can include amachine readable scale. The marking 624 can include a scale visible tothe user. The mounting block 522 can include indicia, such as an arrow,to direct the user visually toward the marking 624. As the moveableinterface 600 translates toward the leg of the user, the marking 624,such as numbers on a scale, can become visible to the user. In someembodiments, the marking 624 can be over a range of from about 0 mm to30 mm. The marking 624 can include a distance measurement of 1 mm, 2 mm,3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, including a range of twoor more of the foregoing values, etc.

2. Femoral System

FIGS. 17A and 17B illustrate the femoral system 552. The femoral system552 can include any of the features of the femoral systems describedherein including femoral system 352. The femoral system 552 can includea femoral baseplate 554. The femoral baseplate 554 can comprise a firstsurface 558 configured to be positioned relative to a portion of thefemur. For example, the first surface 558 of the femoral baseplate 554can be configured to engage the bottom of a bony landmark, such as forexample a femoral condyle. The femoral baseplate 554 can include asecond surface 556, opposite the first surface 558 positioned toward thetibia.

The femoral system 552 can include an extension member 560. In the someembodiments, the extension member 560 can be generally straight. Thefemoral system 552 can include an interface 568. The extension member560 can span between the interface 568 and the femoral baseplate 554.The interface 568 can include a pin or pivot. The interface 568 canallow rotation of the extension member 560 relative to the tibialbaseplate 514. The interface 568 can allow rotation of the femoralbaseplate 554 relative to the tibial baseplate 514. The interface 568can be positioned in the middle of the femur and/or tibia. The interface568 can be aligned with an anatomical feature, such as the intercondylarnotch, Whiteside's Line, or another visible landmark indicating orrelated to the mechanical axis of the femur. In some embodiments, thefemoral baseplate 554 and the interface 568 can be rotationally coupledsuch that rotation of the femoral baseplate 554 causes correspondingrotation of the interface 568. In some embodiments, the femoralbaseplate 554 and the interface 568 can be rotationally coupled via theextension member 560.

The femoral system 552 can include a post mount 566. The extensionmember 560 can position the post mount 566 away from the knee joint. Thefemoral system 552 can include the post 532 described herein. In someembodiments, the post mount 566 can be coupled to the post 532. In someembodiments, the post mount 566 can be integrally or monolithicallyformed with the post 532. In some embodiments, the post mount 566 andthe post 532 form a unitary structure. The translation of the post 532can cause corresponding translation of the post mount 566 as describedherein. The translation of the post 532 can cause correspondingtranslation of the femoral baseplate 554. The translation of the post532 can cause corresponding translation of the extension member 560. Thetranslation of the post 532 can cause corresponding translation of theinterface 568. The translation of the post 532 can cause correspondingtranslation of the other components of the femoral system 552.

In some embodiments, the extension member 560 can extend through thepost mount 566. As described herein, the extension member 560, thefemoral baseplate 554, and the interface 568 can form a unitarystructure such that rotation of the femoral baseplate 554 causescorresponding rotation of the interface 568. The post mount 566 can becoupled to the extension member 560 to allow rotation of the extensionmember 560 relative to the post mount 566. The post mount 566 can becoupled to the femoral baseplate 554 via the extension member 560. Thepost mount 566 can be coupled to the femoral baseplate 554 to allowrotation of the femoral baseplate 554 relative to the post mount 566.The post mount 566 can be coupled to the interface 568 to allow rotationof the interface 568 relative to the post mount 566.

The post mount 566 can include a mounting feature 570. The mountingfeature 570 can allow one or more guides or other instruments to mountto the system 510. The mounting feature 570 can be parallel to thetibial baseplate 514. The mounting feature 570 can be coupled to thepost 532 via the post mount 566. In some embodiments, the mountingfeature 570 can remain in position as the femoral baseplate 554 rotates.The mounting feature 570 can be decoupled from the rotation of theextension member 560. The mounting feature 570 can be decoupled from therotation of the femoral baseplate 554.

The interface 568 can include a second coupler 574. The second coupler574 can be configured to couple with the surgical orientation device 14and/or the reference sensor device 16. The second coupler 574 caninclude any of the features of the couplers described herein. In someembodiments, the second coupler 574 can be positioned on a front surfaceof the interface 568. In some embodiments, the second coupler 574 can bepositioned such that the longitudinal axis of the second coupler 574aligns or is parallel to the femoral baseplate 554.

Referring back to FIG. 13E, in some embodiments, as the femoralbaseplate 554 rotates relative to the tibial baseplate 514, theinterface 568 rotates relative to the tibial baseplate 514. In someembodiments, as the femoral baseplate 554 rotates relative to the tibialbaseplate 514, the surgical orientation device 14 rotates relative tothe tibial baseplate 514. In some embodiments, as the femoral baseplate554 translates relative to the tibial baseplate 514 via the post 532,the interface 568 translates via translation of the post mount 566. Insome embodiments, as the femoral baseplate 554 translates relative tothe tibial baseplate 514 via the post 532, the surgical orientationdevice 14 translates relative to the tibial baseplate 514. FIG. 13Eshows a perspective view of the system 510.

The femoral system 552 can include a bracket 576. The second coupler 574can be configured to couple with the bracket 576. The surgicalorientation device 14 can be configured to couple with the bracket 576.The bracket 576 can include an additional or alternative coupler asdescribed herein.

As shown in FIGS. 13E, 18A, and 18B, femoral system 552 can comprise aresection guide 580. The post mount 566 can include the mounting feature570. The mounting features 570 can be recesses or protrusions to coupleto the resection guide. The mounting feature 570 can allow a quickconnection between the femoral system 552 and the resection guide 580.Other modes of coupling the resection guide 580 to the post mount 566are contemplated.

The resection guide 580 can include one or more notches 582. In someembodiments, each notch 582 can form a right angle cutout. The notch 582can extend through the entire resection guide 580. In some embodiments,each notch 582 can form a step on the resection guide 580. While aplurality of notches 582 are shown creating five steps, differentnumbers, sizes, shapes, and/or locations of notches 582 can also beused. The notches 582 can be in any increment, such as 0.5 mmincrements, 1 mm increments, 1.5 mm increments, 2 mm increments, etc. Insome embodiments, the notch 582 on the right side of the resection guide580 corresponds with notch 582 on the left side of the resection guide580. In some embodiments, each notch 582 is aligned or coaxial withanother notch 582.

The resection guide 580 can include one or more markings 588. Themarking 588 can indicate a value related to the corresponding notch 582.The marking 588 can indicate a distance measurement related to the notch582. The markings 588 can range from 8 mm to 16 mm. The markings 588 canindicate a distance of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29mm, 30 mm, or any range of the foregoing measurements. The markings 588can be used as guides for a femoral cut by indicating a distance fromthe tibial resection. In some embodiments, the marking 588 on the rightside of the resection guide 580 correspond with the marking 588 on theleft side of the resection guide 580. In some embodiments, each notch582 has one marking 588. In some embodiments, each notch 582 has acorresponding notch 582 with the same marking 588.

In some methods, when the system 510 has distracted a distal femoralcondyle or condyles in a knee replacement procedure, the user can markthe femur at the notch 582. In some methods, the user can mark a dot onthe right side of the resection guide 580 and the user can mark a dot onthe left side of the resection guide 580 corresponding notches 582 withthe same marking 588. In some methods, the user can mark a line on theright side of the resection guide 580 and the user can mark a line onthe left side of the resection guide 580 corresponding notches 582 withthe same marking 588. In some methods, the user can mark intersectinglines on the right side of the resection guide 580 and the user can markintersecting lines on the left side of the resection guide 580corresponding notches 582 with the same marking 588. In someembodiments, the user can remove the resection guide 580. In someembodiments, the user can connect the markings on the femur to form aline. In some methods, the line can serve as guide for the posteriorresection.

The notches 582 can be spaced apart from one another in a pattern orpatterns. In some embodiments, the notches 582 can be spaced atincremental steps. The notches 582 can be spaced at regular or irregularintervals. The notches 582 can indicate a distance to the tibialbaseplate 514 via the markings 588. The notches 582 can indicate adistance to the resected tibial surface. In some embodiments, one ormore parallel rows of notches 582 are provided. The rows can be parallelto the tibial baseplate 514 and/or the resected tibial surface. The oneor more parallel rows of notches 582 can allow the user to mark the linefor the posterior resection, as described herein. The one or moreparallel rows of notches 582 can allow the user to mark a resection lineat a known distance from the tibial resection. The one or more parallelrows of notches 582 can be used to ensure that the posterior femoral cutis parallel to the tibial resection.

In some embodiments, the resection guide 580 can provide notches 582 foreven measurements (e.g., 8 mm, 10 mm, 12 mm, 14 mm, 16 mm etc.). In someembodiments, the resection guide 580 can provide notches 582 for oddmeasurements (e.g., 7 mm, 9 mm, 11 mm, 13 mm, 15 mm, 17 mm etc.). Theresection guide 580 can include a first portion extending in a firstdirection. The resection guide 580 can include a second portionextending in a second direction, the second direction different than thefirst direction. In some embodiments, the resection guide 580 has twoportions which are perpendicular or substantially perpendicular. Thefirst portion can be configured to be adjacent to the femur and thesecond portion can be configured to extend away from the femur. Thefirst portion and the second portion can be substantially flat orplate-like. The resection guide 580 can be L-shaped. The second portioncan include a slot 584 configured to accept a thumbscrew 586. Thethumbscrew 586 can removably extend the length of the resection guide580. The thumbscrew 586 can allow the user to move the resection guide580 against the femur.

The resection guide 580 can include a portion to engage the mountingfeature 570 of the post mount 566. The resection guide 580 can couple tothe mounting feature 570 of the post mount 566 such that translation ofthe post 532 causes corresponding translation of the resection guide580. The system 510 can translate such that the resection guide 580remains parallel to the tibial baseplate 512. The resection guide 580can be a modular device. The resection guide 580 can be coupled anddecoupled to the mounting feature 570 during the procedure as needed.

Other guides are contemplated. The system 510 can be utilized with anyguide described herein. The system 510 can be utilized with a drillguide to facilitate placements of a pin or pins into the distal femur.In some embodiments, the system 510 can include a plurality of resectionguides configured to couple to the mounting feature 570. In someembodiments, the plurality of resection guides can include differentnotches to enable different posterior resection cuts. Other devices canbe mounted to the mounting feature 570. Other configurations of couplingthe resection guide 580 to the system 510 are contemplated.

Referring to FIGS. 13E and 18A, the resection guide 580 can bemaintained in a rotational orientation relative to the tibial baseplate514. The resection guide 580 can be coupled or decoupled from themounting features 570. The mounting features 570 can be coupled to thepost mount 566. In some embodiments, the post mount 566 can maintain theposition of the resection guide 580 relative to the tibial baseplate.The post mount 566 is coupled to the post 532 in a manner to reduce orprevent rotation of the post mount 566 relative to the post 532. Thepost 532 is coupled to the tibial baseplate 514 via the tibial mountingblock 522 in a manner to reduce or prevent rotation of the post 532relative to tibial baseplate 514. The resection guide 580 can berotationally stabilized relative to the tibial baseplate 514. Theresection guide 580 can be rotationally coupled to the tibial baseplate514. The resection guide 580 can be parallel to the tibial baseplate514. The resection guide 580 can be parallel to the tibial resection.

Referring to FIGS. 13E and 18A, the femoral baseplate 554 can rotaterelative to the tibial baseplate 514. The femoral baseplate 554 can becoupled to the interface 568. The surgical orientation device 14 can becoupled to the interface 568. The surgical orientation device 14 canmeasure the rotation of the femoral baseplate 554. In some embodiments,the femoral baseplate 554 can rotate relative to the resection guide580. In some embodiments, the femoral baseplate 554 can rotate relativeto post mount 566. In some embodiments, the femoral baseplate 554 canrotate relative to the post 532.

The resection guide 580 can be rotationally decoupled from the femoralbaseplate 554. The femoral baseplate 554 can be at any angle relative tothe resection guide 580. The femoral baseplate 554 can be at any anglerelative to the tibial resection. In some embodiments, the rotation ofthe femoral baseplate 554 is independent of the positioning of theresection guide 580. The resection guide 580 can translate relative tothe tibial baseplate 514. The resection guide 580 can translate as thepost 532 translates. The system 510 can provide an alignment of theresection guide 580 relative to the tibial resection as describedherein.

3. Distraction Overview

FIG. 19A-19H illustrate additional views of the system 510 coupled tothe tibia and femur of a patient. FIG. 19A illustrates a perspectiveview of a position of the system 510. FIG. 19B illustrates a front viewof a position of the system 510. The femoral system 552 can include thebracket 576 as described herein. The bracket 576 can enable the user toview the joint space. The bracket 576 can move the surgical orientationdevice 14 downward relative to the femoral baseplate 554. The surgicalorientation device 14 can be located out of the joint space. The usercan view the tibial baseplate 514 and the femoral baseplate 554. Thebracket 576 can offset the surgical orientation device 14 to the side.

In some embodiments, the bracket 576 can be generally L-shaped. Thebracket 576 can include a first portion 562 that extends from the secondcoupler 574. The first portion 562 can extend in a first direction. Thebracket 576 can include a second portion 564. The second portion 564 canextend in a second direction; the second direction can be different fromthe first direction. In some embodiments, the first portion 562 canextend horizontally. In some embodiments, the second portion 564 canextend vertically. In some embodiments, the second portion 564 canextends perpendicularly or generally perpendicularly from the firstportion 562. In some embodiments, the first portion 562 is straight orsubstantially straight. In some embodiments, the first portion 562 isnon-linear, for instance having a straight segment and a diagonalsegment. In some embodiments, the second portion 564 is straight orsubstantially straight. In some embodiments, the first portion 562 canbe integrally or monolithically formed with the second portion 564. Insome embodiments, the first portion 562 can extend in a diagonal fromthe second coupler 574 to provide an offset. In some embodiments, thefirst portion 562 can extend straight from the second coupler 574.

An advantage can be that the bracket 576 can position the surgicalorientation device 14 below the tibial resection. An advantage can bethat the bracket 576 can position the surgical orientation device 14 outof a field of view of the joint space, e.g. enhancing visibility fromthe perspective of FIG. 19A. An advantage can be that the bracket 576can position the surgical orientation device 14 offset from thereference sensor device 16. An advantage is that the bracket 576 canposition the surgical orientation device 14 offset from the interface538 of the adjustment device 536. An advantage is that the bracket 576can position the surgical orientation device 14 below the resectionguide 580. The surgical orientation device 14 can be positioned to allowa line of sight to the resection guide 580. Other configurations arecontemplated.

In some embodiments, the longitudinal axis of the reference sensordevice 16 can align with the longitudinal axis of the tibia. The axis ofthe tibia can be perpendicular to the tibial resection. In someembodiments, the reference sensor device 16 can align with a mechanicalaxis associated with the knee joint, e.g., of the tibia or the leg. Insome embodiments, the longitudinal axis of the surgical orientationdevice 14 can be offset from the longitudinal axis of the tibia. In theillustrated embodiment, the surgical orientation device 14 can be offsetfrom a mechanical axis associated with the knee joint, e.g., of thetibia or the leg. The longitudinal axis of the surgical orientationdevice 14 and the longitudinal axis of the reference sensor device 16can be parallel. The longitudinal axis of the surgical orientationdevice 14 and the longitudinal axis of the reference sensor device 16can be offset in the coronal plane. The longitudinal axis of thesurgical orientation device 14 and the longitudinal axis of thereference sensor device 16 can be offset in the sagittal plane. Thelongitudinal axis of the surgical orientation device 14 and thelongitudinal axis of the reference sensor device 16 can be offset in thetraverse plane.

FIG. 19C illustrates a perspective view of a position of the tibialsystem 512 and the post 532. As described herein, the upper portion 542of the post 532 can have a substantially round or circularcross-sectional shape and the guide portion 530 of the mounting block522 can have a corresponding substantially round or circularcross-sectional shape. The round or circular cross-sectional shape canallow for more precision in placement of the markings 540 relative tothe camera 344 of the reference sensor device 16. The round or circularcross-sectional shape can allow the tibial baseplate 514 and the femoralbaseplate 554 to maintain alignment during distraction. The round orcircular cross-sectional shape can allow a tighter tolerance betweencomponents of the system 510. The lower portion 546 of the post 532 canhave any cross-sectional shape.

FIG. 19D illustrates a cross-sectional view inside the mounting block522. The adjustment device 536 and the catch 548 can be diametricallyopposed. The adjustment device 536 and the catch 548 can be spacedapart. The adjustment device 536 can be configured to engage the rack534 which can have larger gears than the ratchet 550 engaged by thecatch 548. The adjustment device 536 can allow application of force. Theforce exerted can be in the range of 150 N to 200 N. The adjustmentdevice 536 and the rack 534 can be configured to exert any forcesufficient for joint distraction. The teeth on adjustment device 536 andthe teeth of the rack 534 can be configured to exert a desired force onthe joint. The catch 548 can allow fine resolution positioning. Theincrements between teeth on the ratchet 550 can be smaller than the rack534. The teeth can be in 1 mm increments on the ratchet 550. The catch548 can maintain the position of the post 532 when the user stopsactuating the adjustment device 536.

FIG. 19D illustrates the connection between other components of thesystem 510. The post 532 can be coupled to the post mount 566.Translation of the post 532 can cause corresponding translation of thepost mount 566. The resection guide 580 can be coupled to the post mount566 via the mounting feature 570. In some embodiments, rotation islimited or prevented between the post 532 and the post mount 566. Insome embodiments, rotation is limited or prevented between the post 532and the resection guide 580. In some embodiments, the post 532 and thepost mount 566 can function as a unit. In some embodiments, the post 532and the post mount 566 are integrally formed. In some embodiments, theresection guide 580 is removably mounted to the mounting feature 570 ofthe post mount 566. In some embodiments, when the resection guide 580 iscoupled to the mounting feature 570, the post 532, the post mount 566,and the resection guide 580 form a unitary structure. In someembodiments, the resection guide 580 can be configured only to translatelinearly with translation of the post 532.

FIG. 19D illustrates the connection between the extension member 560 andthe post mount 566. The extension member 560 can couple to the femoralbaseplate 554. The extension member 560 can couple to the interface 568(see FIG. 17A). Rotation of the femoral baseplate 554 can causecorresponding rotation of the extension member 560. The post mount 566can allow rotation of the femoral baseplate 554 and the extension member560 relative to the post mount 566.

FIGS. 19E and 19F illustrate the tibial system and the moveableinterface 600. FIG. 19E illustrates the moveable interface 600 spacedapart from the tibia. FIG. 19F illustrates the moveable interface 600engaged with the tibia. The moveable interface 600 can include thesurface 602 to contact the shin of the user. The moveable interface 600can be configured to move in the fore and aft direction within themounting block 522 (corresponding to posterior and anterior movementrelative to the patient). The moveable interface 600 can slide in thefore direction to rest against the shin of the patient. The moveableinterface lock can be used to reduce or prevent the sliding movement ofthe moveable interface 600. The moveable interface lock can include thehandle 622 which can rotate the turnbuckle 612 within the mounting block522 as described herein. The frictional force of the moveable interfacelock can limit sliding movement of the moveable interface 600.

The moveable interface 600 can include the marking 624. The marking 624can provide an indication of the insertion depth of the system 510. Themoveable interface 600 can limit or prevent further insertion by theinterference between the moveable interface 600 and the anatomy of thepatient. The moveable interface 600 can increase the stability of thesystem 510. The moveable interface 600 can provide an additional pointof contact between the system 510 and the patient. The moveableinterface 600 can limit insertion depth in flexion. The moveableinterface 600 can limit insertion depth in extension.

FIG. 19G illustrates a perspective view of the one or more notches 582of the resection guide 580. The notches 582 can indicate the distance tothe tibial resection. The resection guide 580 can be a plate configuredto rest against the resected femur. Each notch 582 or some of thenotches 582 can include a corresponding marking 588. The notches 582 canenable a user to draw a line at the position of the posterior cut. Insome methods, the user can mark the femur using one or more notches 582.In some methods, the user can then connect the marks on the femur toform a line. The line can correspond to a resection plane.

FIG. 19H illustrates a perspective view of the system 510 and a torquedriver 650. The torque driver 650 can engage the adjustment device 536.The interface 538 of the adjustment device 536 can be located on themounting block 522. The torque driver 650 can allow rotation of theadjustment device 536. In some embodiments, rotation of the torquedriver 650 can cause corresponding rotation of the adjustment device536. In some embodiments, translation of the torque driver 650 can causecorresponding rotation of the adjustment device 536. In someembodiments, a motion or movement of the torque driver 600 can causecorresponding rotation of the adjustment device 536. While FIG. 19Hillustrates a torque driver 650, other drivers are contemplated.

The system 510 can facilitate a posterior resection. The posteriorresection can enable the positioning of the implant. The implantmanufacturer can supply a guide configured to mount to a femur after theposterior resection. The anterior and/or chamfer cut can be relative tothe posterior resection. The drill guide and the positioning of thecutting block can be relative to the posterior resection. The notches582 can serve to mark the femur for the posterior resection cut. Theresection guide 580 can allow the user to mark the femur a certaindistance from the tibia resection for the posterior resection cut.

The surgical orientation device 14 can measure the distance for theposterior resection cut. The surgical orientation device 14 and thereference sensor device 16 can be in communication to determine thedistraction distance. In some methods, the camera 344 of the referencesensor device 16 can capture a distance measurement from marking 540 ofthe post 532. In some embodiments, the reference sensor device 16 cantransmit the distance measurement to the surgical orientation device 14.In some embodiments, the reference sensor device 16 can transmit theimage from the camera 344 to the surgical orientation device 14.

The system 510 can be configured to be inserted within the joint space.In some embodiments, the tibial baseplate 514 can be adjacent to thefemoral baseplate 554 during insertion. The surgical orientation device14 can be coupled with the bracket 576. The reference sensor device 16can be coupled with the mounting block 522. The femoral system 552 canbe moved up and down (e.g. proximally and distally) relative to thetibial system 512 by the adjustment device 536. The adjustment device536 can be used to distract the femur relative to the tibia. Theadjustment device 536 can be actuated by the user to translate the post532 within the mounting block 522. The catch 548 can maintain theposition of the post 532 when the user stops actuating the adjustmentdevice 536. The catch 548 can prevent positional slippage of theadjustment device 536. The movement of the post 532 can causecorresponding movement of the femoral system 552 relative to the tibialsystem 512. The femoral system 552 translates as a unit with the post532. By translation of the post 532, the femoral baseplate 554 can bemoved relative to the tibial baseplate 514 to increase or decrease a gaptherebetween.

In some embodiments, the femoral baseplate 554 can rotate relative tothe tibial baseplate 514. The femoral baseplate 554 can rotate in themedial-lateral direction. This rotation can allow the femoral baseplate554 to engage both femoral condyles, regardless of size or orientationof the femoral condyles or spacing of the femoral condyles. Thisrotation can allow the femoral baseplate 554 to be inserted through arelatively narrow incision in a low profile orientation, and then rotatewithin the joint space to engage the femoral condyles.

The surgical orientation device 14 can be coupled to the femoralbaseplate 554. The surgical orientation device 14 can provide anindication of the degree of rotation of the femoral baseplate 554. Thesurgical orientation device 14 can be coupled to the femoral baseplate554 such that rotation of the femoral baseplate 554 can causecorresponding rotation of the surgical orientation device 14. Thesurgical orientation device 14 can include a display 26 which canindicate the angle of rotation of the surgical orientation device 14. Insome embodiments, the surgical orientation device 14 and the referencesensor device 16 determine the angle of the surgical orientation device14. In some embodiments, one or more sensors within the surgicalorientation device 14 determine the angle of the surgical orientationdevice 14. As one non-limiting example, one or more sensors candetermine position or orientation relative to gravitational zero. Thesurgical orientation device 14 can measure the angle of the femoralbaseplate 554. The angle can correspond to the angle between the femoralbaseplate 554 and the tibial baseplate 514.

In some embodiments, the soft tissue around the knee joint can bereleased. In some embodiments, the soft tissue around the knee joint canbe released when the knee is in extension. In some embodiments, the softtissue around the knee joint can be released when the knee is inextension only. In some embodiments, the soft tissue around the kneejoint can be released when the knee is in flexion. In some methods, theuser can modify the soft tissue by cutting one or more ligaments. Thechange in soft tissue can cause a change in the rotation of the femoralbaseplate 554. The change in rotation of the femoral baseplate 554 cancause a corresponding change in the rotation of the surgical orientationdevice 14. The surgical orientation device 14 can display the angle ofthe surgical orientation device 14 as the surgical orientation device 14rotates. In some embodiments, the user can release one or more ligamentsin the knee joint prior to or during the knee distraction in order tofacilitate simultaneous symmetry of the gaps. In some embodiments, theuser can release one or more ligaments in the knee joint prior to orduring the knee distraction to facilitate mechanical axis alignment. Insome embodiments, the user can release one or more ligaments in the kneejoint prior to or during the knee distraction to facilitate balancing ofthe soft tissue and/or ligaments in the knee joint. The user can nick orcut soft tissue to adjust for laxity of the knee joint. In someembodiments, the user performs soft tissue balancing until the femoralbaseplate 554 and the tibial baseplate 514 are parallel or approximatelyparallel when the knee is in extension. In some embodiments, the userperforms soft tissue balancing until the femoral baseplate 554 and thetibial baseplate 514 are at a desired angle.

The surgical orientation device 14 and/or the reference device 16 can beconfigured to measure rotation of the surgical orientation device 14during soft tissue balancing. The rotation of the surgical orientationdevice 14 is related to the relative tension in the medial and lateralsoft tissue on the medial and lateral sides of the knee joint. Thesurgical orientation device 14 can display the angle of rotation beforesoft tissue release and/or during soft tissue release. The surgicalorientation device 14 can display this information on the display 26located within the surgical field. As described herein, the surgicalorientation device 14 can be positioned below the joint space. Thesurgical orientation device 14 can display the angle of femoralrotation. In some embodiments, the surgical orientation device 14 candisplay the angle of femoral rotation in real-time. In some embodiments,the surgical orientation device 14 can display a static angle of femoralrotation, for instance the angle of femoral rotation at a specific timesuch as when a button or other user input 28 is activated. In someembodiments, the surgical orientation device 14 can display a dynamicangle of femoral rotation, for instance the angle of femoral rotation asthe soft tissue is being manipulated. In some embodiments, the surgicalorientation device 14 can display a target angle of femoral rotation.The target can be displayed as a graphical representation, for instancea slide scale or indicia located on a bullseye.

The surgical orientation device 14 and/or the reference device 16 can beconfigured to measure the distraction distance between the femoralbaseplate 554 and the tibial baseplate 514. The camera 344 can capturean image corresponding to the distraction distance or otherwise read themarking 540 on the post 532. The marking 540 can be a scale which can becaptured by the camera 344. The image from the camera 344 can beinterpreted by either the surgical orientation device 14 or thereference sensor device 16. The surgical orientation device 14 candisplay the distraction distance on the display 26. In some embodiments,the surgical orientation device 14 can display the distraction distancein real-time. In some embodiments, the surgical orientation device 14can display a static distraction distance, for instance the distractiondistance at a specific time such as when a button or other user input 28is activated In some embodiments, the surgical orientation device 14 candisplay a dynamic distraction distance, for instance the distractiondistance as the post 532 is moving. In some embodiments, the surgicalorientation device 14 can display a target distraction distance. Thetarget can be displayed as graphical representation, for instance afillable bar of a bar graph, sliding scale, or indicia located on abullseye.

In some embodiments, the user can make femoral cuts after distraction.The resection guide 580 can be a modular device that can be coupled ordecoupled from the mounting features 570. In some embodiments, theresection guide 580 can be rotationally fixed relative to the tibialbaseplate 514. In some embodiments, the resection guide 580 can allowthe user to make one or more cuts in the femur at an angle selectedrelative to (e.g., parallel to) the tibial baseplate 514. In someembodiments, the resection guide 580 can allow the user to make one ormore cuts in the femur at known distance from the resected tibia. Insome embodiments, the cut can be performed when the knee is in flexion.

In some methods of use, the tibia is resected prior to using the system510. For example, and as described above, a tibial preparation system210 or other tibial preparation system can be used to resect a portionor portions of the tibia, such that the distal end of the tibiacomprises generally a flat plane. In some methods of use, the femur isresected prior to using the system 510. For example, and as describedabove, a femoral preparation system 10 or other femur preparation systemcan be used to resect a portion or portions of the femur, such that thedistal end of the femur comprises generally a flat plane.

In some embodiments, the system 510 can be used when the knee is inextension. In some methods of use, after completing the tibial resectionand the distal femoral resection, the user flexes the knee to 180degrees and inserts the system 510. In some methods of use, the leg ispositioned in full extension (not shown). The tibial baseplate 514 andthe femoral baseplate 554 can be inserted into the knee joint and theknee joint can be distracted. The surgical orientation device 14 canmeasure the distraction distance using one or more sensors. Thereference sensor device 16 can measure the distraction distance usingone or more sensors. The reference sensor device 16 can measure thedistraction distance using the camera 344. The surgical orientationdevice 14 and/or the reference sensor device 16 can record thedistraction distance when the knee is in extension. The surgicalorientation device 14 and/or the reference sensor device 16 can storethe distraction distance when the knee is in extension for use when theknee is in flexion. The surgical orientation device 14 and the femoralbaseplate 554 can rotate based on the tension on the medial and lateralsides of the knee. The user can release ligaments when the knee is inextension based on the angle output of the surgical orientation device14. The user can release ligaments to decrease the rotation of thefemoral baseplate 554. The user can release ligaments so that thefemoral baseplate 554 is parallel to the tibial baseplate 514. The usercan release ligaments so that the femoral baseplate 554 is at a desiredangle relative to the tibial baseplate 514. In some methods, soft tissuerelease is only performed with the knee in extension.

In some embodiments, the system 510 can be used when the knee is inflexion. In some methods of use, after completing the tibial resectionand the distal femoral resection, the user flexes the knee to 90 degreesand inserts the system 510. The tibial baseplate 514 and the femoralbaseplate 554 can be inserted into the knee joint and the knee joint canbe distracted. The surgical orientation device 14 can measure thedistraction distance using one or more sensors. The reference sensordevice 16 can measure the distraction distance using one or moresensors. The reference sensor device 16 can measure the distractiondistance using the camera 344. The surgical orientation device 14 and/orthe reference sensor device 16 can record the distraction distance whenthe knee is in flexion. The surgical orientation device 14 and/or thereference sensor device 16 can compare the distraction distance when theknee is in extension and flexion. The surgical orientation device 14 andthe femoral baseplate 554 can rotate based on the tension on the medialand lateral sides of the knee. The surgical orientation device 14 candisplay the angle of rotation of the femoral baseplate. The resectionguide 580 can be parallel to the tibial resection. After the joint isdistracted, the user can mark the resection line for the posterior cut.In some methods, the user can balance the gaps in flexion and extension.In some methods, the user can balance the gaps in flexion and extensionby selecting a notch 582 on the resection guide 580 corresponding to theextension gap.

As described herein, the camera 344 can capture an image related to thedistraction distance. The distance measurement can correspond to thedistraction distance between the tibia and the femur. The system 510 cancalculate the anterior-posterior shift to equalize the flexion gap andthe extension gap. In some embodiments, the surgical orientation device14 can display the distraction distance in extension and the distractiondistance in flexion. In some embodiments, the surgical orientationdevice 14 can display a static distraction distance from measurementstaken while the knee was in extension and a dynamic distraction distancewhen the knee is in flexion. In some methods, the user can compare thedistraction distances in extension and in flexion. In some methods, thesurgical orientation device 14 can output the difference in theextension gap and the flexion gap.

In some knee joint procedures, a posterior femoral cut (PFC) is madewhile the knee is in flexion. In some methods of use, the user canutilize the resection guide 580 to perform the posterior cut. Theresection guide 580 can include notches corresponding to different gapmeasurements. The resection guide 580 can provide a guide to mark theposterior resection to provide the appropriate anterior-posterior shift.The anterior-posterior shift can be based on the anterior-posteriorshift calculated by the surgical orientation device 14. Theanterior-posterior shift can be based on the anterior-posterior shiftdetermined by comparing the distraction distance in extension and thedistraction distance in flexion. The anterior-posterior shift can bedifference between the gap in extension and flexion.

The user can select a notch 582 which corresponds to the measured gap inextension. The notch 582 can include a corresponding marking 588 whichcan be a distance measurement. For instance, if the extension gap is 8mm, then the user can select a notch 582 corresponding to a flexion gapof 8 mm. The user can select from different parallel rows of notches 582corresponding to different distances. The user can use a row of notches582 to make two marks on the femur. In some methods, the user can removethe resection guide 580 and interconnect the marks to form a line. Theuser can use the marks and/or the line to make the posterior femoralcut. The anterior cut can be made relative to the posterior cut. Thechamfer cut can be made relative to the posterior cut. One or moreadditional cuts can be made based on the posterior femoral cut.

The system 510 can be utilized for soft tissue balancing in extensionand/or flexion. The surgical orientation device 14 can display therotation angle of the surgical orientation device 14. The rotation anglecan be relative to the reference sensor device 16. The rotation anglecan be relative to gravitational zero, or any other vertical orhorizontal vector. The surgical orientation device 14 can display therotation angle of the surgical orientation device 14. The surgicalorientation device 14 can display the rotation angle of the surgicalorientation device 14 relative to a vertical vector. The surgicalorientation device 14 can display the rotation angle of the surgicalorientation device 14 relative to a horizontal vector. The surgicalorientation device 14 and/or the reference sensor device 16 can includeone or more sensors to determine the direction of gravity. In someembodiments, the surgical orientation device 14 and/or the referencesensor device 16 can include an accelerometer.

The rotation angle of the surgical orientation device 14 can correspondto the posterior condyle angle. The system 510 can record the angle ofrotation in extension and/or flexion. The rotation angle of the surgicalorientation device 14 can correspond to the posterior condyle anglerelated to an implant or implant guide. In some embodiments, the cuttingblock or drill guide provided with the implant by the implantmanufacturer can be adjustable based on the posterior condyle angle. Insome embodiments, an implant from a plurality of implants can beselected based on the posterior condyle angle.

The system 510 can perform one or more calculations related to therotation angle of the surgical orientation device 14. The system 510 canperform one or more calculations related to the distraction distance.The system 510 can be utilized to provide a visual indication of themedial distraction distance. The system 510 can be utilized to provide avisual indication of the lateral distraction distance. The system 510can be configured to measure the tension within the soft tissue on themedial and/or lateral sides of the knee joint. The surgical orientationdevice 14 can be configured to display the force or tension on eachside.

In some embodiments, the user can release one or more ligaments in theknee joint to balance the soft tissue on the medial and/or lateral sidesof the knee joint. The user can release soft tissue when the knee is inextension for symmetry of the extension gap. The user can release softtissue when the knee is in flexion for symmetry of the flexion gap. Theuser can release soft tissue when the knee is in extension or flexionfor mechanical axis alignment between the femur and the tibia. The usercan release soft tissue to reduce the rotation angle of the surgicalorientation device 14. The user can release soft tissue to increase therotation angle of the surgical orientation device 14. In some methods,the user can nick or cut soft tissue to adjust for laxity of the kneejoint. The user can perform soft tissue balancing until the tibia andthe femur are at the desired angle. The user can perform soft tissuebalancing until the surgical orientation device 14 displays the desiredangle. In some methods, the soft tissue is modified only in extension.In some methods, the soft tissue is modified only in flexion. In somemethods, the soft tissue is modified in both flexion and extension. Insome methods, the soft tissue is not modified.

D. Advantages

The Total Knee Arthroplasty (TKA) market is divided. Systems typicallyfocus on alignment or balancing. For alignment system, there is measuredresection. The resection or cut is aligned with bony or anatomiclandmarks. Tension is subsequently addressed. For balancing systems,there is gap balancing. The soft tissue or ligaments in the knee jointare balanced. There are typically rectangular cuts on the balanced knee.

FIGS. 20A-20B illustrate the system 310. FIGS. 20C-20D illustrate thesystem 510. FIGS. 20A and 20C, illustrate the systems 310, 510 indistraction positions wherein the tibial system 312, 512 is separated adistance from the femoral system 352, 552. As described herein, thisseparation can be achieved by an actuation system including the post332, 532. For instance, a rack and pinion can be utilized to exert aforce. The femoral system 352, 552 translates relative to the tibialsystem 312, 512 due to the movement of the post 332, 532. The femoralsystem 352, 552 is translationally coupled to the post 332, 532. Asdescribed herein, the femoral system 352, 552 can include the post mount366, 566 that translate the femoral system 352, 552 with the post 332,532. The resection guide 580 or the drill guide 380 can be coupled tothe post mount 366, 566 such that the resection guide 580 or the drillguide 380 translates with the femoral system 352, 552.

FIGS. 20B and 20D, illustrate the systems 310, 510 in a distraction androtation positions wherein the tibial system 312, 512 is separated adistance from the femoral system 352, 552 and the femoral system 352,552 is rotated relative the tibial system 312, 512. As described herein,the femoral system 352, 552 can include a femoral baseplate 354, 554that can be configured to rotate relative to the post 332, 532. Asdescribed herein, the femoral baseplate 354 is coupled to extensionmember 360 which includes the second coupler 374. The femoral baseplate354 and the second coupler 374 form a unitary structure that isconfigured to rotate about the rotational interface 368. As describedherein, the femoral baseplate 554 is coupled to extension member 560which extends through the post mount 566 to the interface 568. Theinterface 568 includes the second coupler 574. Rotation of the femoralbaseplate 554 along one axis changes to rotation of the interface 568about a second axis. In some embodiments, the system 510 converts therotation about one axis to a rotation about the other axis to improveaccuracy of the inertial sensors. The interface 568 can pivot upward anddownward as the femoral baseplate 554 is rotated. While all of thecomponents of the femoral system 552 are rotationally linked, theinterface 568 rotates about a different axis of rotation than thefemoral baseplate 554.

The system 310, 510 can be integrated with the femoral preparationsystem 10 and/or the tibial preparation system 210 described herein. Thesystem 310, 510 provides a solution for balancing. The system 310, 510integrates soft tissue balancing functionality. The system 310, 510 issimple, streamlined system that can be integrated in the workflow withalignment systems. The femoral preparation system 10, the tibialpreparation system 210 and/or the system 310 can allow the user toproduce an aligned, balance posterior condyle cut.

The femoral preparation system 10, the tibial preparation system 210and/or the system 310, 510 can provide angular precision and accuracyvia the inertial sensors. The femoral preparation system 10, the tibialpreparation system 210 and/or the system 310, 510 utilize the surgicalorientation device 14 and/or the reference sensor device 16. Thesurgical orientation device 14 and/or the reference sensor device 16comprise one or more inertial sensors as described herein. The surgicalorientation device 14 and/or the reference sensor device 16 comprise oneor more accelerometers. The surgical orientation device 14 and/or thereference sensor device 16 comprise one or more gyroscopes.

The femoral preparation system 10, the tibial preparation system 210and/or the system 310, 510 can provide a controlled, known distractionforce. The post 332, 532 can be translated via the adjustment device336, 536. In some embodiments, the rotation of the adjustment device336, 536 can correlate with a known force or pressure. In someembodiments, one rotation of the adjustment device 336, 536 cancorrespond to 40-50 N of force, and two rotations of the adjustmentdevice 336, 536 can correspond to 80-100 N of force. In someembodiments, the adjustment device 336, 536 can be configured to exertbetween 150 N and 200 N of force. In some embodiments, the tibialbaseplate 314, 514 can include one or more sensors to measure force. Insome embodiments, the femoral baseplate 354, 554 can include one or moresensors to measure force. The surgical orientation device 14 and/or thereference sensor device 16 can record the force measurement. Thesurgical orientation device 14 and/or the reference sensor device 16 andstore the force measurement.

The femoral preparation system 10, the tibial preparation system 210and/or the system 310, 510 can include an in-field graphic userinterface. The femoral preparation system 10, the tibial preparationsystem 210 and/or the system 310, 510 can include the surgicalorientation device 14. The surgical orientation device 14 can includethe display 26. The display 26 can provide an on-screen graphic of oneor more parameters to be used during the procedure. For example, anumerical display can be provided for one or more measurements, such asflexion-extension angles, varus-valgus angles, rotation angles (e.g.angles of rotation about the mechanical axis of the leg, the angle ofthe posterior condyles, etc.), or distances (e.g., extension distancesof the post 332, 532). The on-screen graphic can comprise alphanumerictext or symbols of various colors, one or more background colors, one ormore icons, one or more GUI images, animations, arrows, and the like.The display 26 can also provide a textual, audible, or other visualnotification to the user that the current measurements are outside apre-determined range. The surgical orientation device 14 can becontrolled by the user within the surgical field. The user can view thedisplay 26 within the surgical field. The user can interact with thesurgical orientation device 14 within the surgical field (e.g., depressa button, record a measurement, receive instructions, interact with userinput 28, read display 26, etc.).

The femoral preparation system 10, the tibial preparation system 210and/or the system 310, 510 can be open platform. The system 310, 510 canwork with leading implants. The drill guide 380 can be provided by theimplant manufacturer. The drill guide 380 can provide openings 382corresponding to measurements for cutting blocks provided by the implantmanufacturers. The openings 382 can correspond with a cutting block 394provided by the implant manufacturer. The system 310 can provide a drillguide 380 for 4-in-1 block alignment to tibial resection. The drillguide 380 can be used to make holes that will locate the cutting block394, as described herein. The resection guide 580 can be utilized tomark a line on the femur. In some embodiments, the resection guide 580includes notches 582 which enable the user to draw a dot, line or tickmark corresponding to the notch 582. These marks can then be used todraw a line once the resection guide 580 is removed. Otherconfigurations are contemplated to draw a resection line. The resectionguide 580 can include one or more openings to draw a dot. The resectionguide 580 can include one or more slots to draw a line or line segment.The resection guide 580 can include one or more flat surfaces to draw aline or line segment. Other configurations of marking a resection lineare contemplated.

The system 310, 510 can calculate, display, record, and store variousmeasurements and/or calculations. The data can be stored during thelength of the procedure. The data can be stored for post-operative use.The system 310, 510 can calculate the angle of the posterior condyles.The system 310, 510 can display the angle of the posterior condyles. Thesystem 310, 510 can record the angle of the posterior condyles. Thesystem 310, 510 can store the angle of the posterior condyles. Asdescribed herein, the system 310, 510 can allow for the placement of thereference sensor device 16 in two or more orientations when the system310, 510 calculates the angle of the posterior condyles. The system 310,510 can allow for the placement of the reference sensor device 16 in twoperpendicular orientations. The longitudinal axis of the referencesensor device 16 can be parallel to the tibial baseplate 314, 514 whenthe system 310, 510 calculates the angle of the posterior condyles. Thelongitudinal axis of the surgical orientation device 14 can beperpendicular to the tibial baseplate 314 when the system 310, 510calculates the angle of the posterior condyles.

The system 310, 510 can calculate the distraction distance in extension.The system 310, 510 can display the distraction distance in extension.The system 310, 510 can record the distraction distance in extension.The system 310, 510 can store the distraction distance in extension. Thesystem 310, 510 can calculate the distraction distance in flexion. Thesystem 310, 510 can display the distraction distance in flexion. Thesystem 310, 510 can record the distraction distance in flexion. Thesystem 310, 510 can store the distraction distance in flexion. Thesystem 310, 510 can compare the distraction distance in flexion and thedistraction distance in extension. The system 310, 510 can calculate anadjustment distance if the distraction distance in flexion and thedistraction distance in extension are different. The user can adjust thedrill guide 380 by the adjustment distance. The user can utilizeparallel rows of openings 382 separated by the adjustment distance. Theuser can utilize the resection guide 580 related to the distractiondistance. The user can utilize parallel rows of notches 582 to mark aline for the posterior cut.

The system 310, 510 can calculate the medial distraction distance. Thesystem 310, 510 can calculate the lateral distraction distance. Themedial distraction distance and the lateral distraction distance can bedetermined based in part on the distraction distance. The medialdistraction distance and the lateral distraction distance can bedetermined based in part on the angle of the posterior condyles. Thesystem 310, 510 can display the medial distraction distance. The system310, 510 can display the lateral distraction distance. The system 310,510 can record the medial distraction distance. The system 310, 510 canrecord the lateral distraction distance. The system 310, 510 can storedistraction distance. The system 310, 510 can store the lateraldistraction distance. The system 310, 510 can provide medial distractiondistance and/lateral distraction distance dynamically. The system 310,510 can provide medial distraction distance and/lateral distractiondistance in real-time.

The system 310, 510 can provide cut verification. The system 310, 510can provide cut verification of the distal femoral cut (DFC). The DFCremoves a distal (i.e., lower) portion of the femur. The system 310, 510can provide cut verification of the posterior femoral cut (PFC). The PFCremoves a portion of the posterior condyle. The system 510 can beutilized to mark the femur related to the PFC. The system 310, 510 canprovide cut verification for one or more cuts of the femur. The system310, 510 can provide cut verification for one or more cuts of the tibia.

The system 310, 510 can utilize the surgical orientation device 14and/or the reference sensor device 16 of the femoral preparation system10 and the tibial preparation system 210 described herein. The system310, 510 can provide an attachment for the surgical orientation device14. The system 310, 510 can provide an attachment for the referencesensor device 16. The system 310, 510 can provide an attachment for thedrill guide 380. The system 310, 510 can allow attachment of theresection guide 580. The systems described herein can be compatible withany subsystem described herein including the guides described herein.The drill guide 380 can couple to the tibial baseplate 314. The drillguide 380 can be rotationally independent from the femoral baseplate354. The drill guide 380 guides drill holes to 4-in-1 blockspecifications. The drill guide 380 can guide the cutting block to beparallel to the tibial resection. The resection guide 580 can couple tothe tibial baseplate 514. The resection guide 580 can be rotationallyindependent from the femoral baseplate 554. The resection guide 580 canguide the posterior cut to be parallel to the tibia resection.

The system 310, 510 can provide a distraction force. The system 310, 510can mechanically distract in extension and flexion. The system 310, 510can provide a known distraction force. In some embodiments, the knowndistraction force is between 80 N and 100 N. In some embodiments, thedistraction force is between 150 N and 200 N. In some embodiments, theknown distraction force is greater than 50 N, greater than 60 N, greaterthan 70 N, greater than 80 N, greater than 90 N, greater than 100 N,greater than 110 N, greater than 120 N, greater than 130 N, greater than140 N, greater than 150 N, greater than 160 N, greater than 170 N,greater than 180 N, greater than 190 N, greater than 200 N, greater than210 N, greater than 220 N, greater than 230 N, greater than 240 N,greater than 250 N, etc.

The display 26 can provide a different way to determine the distractiondistance than visual inspection of a scale. The display 26 can provide adigital output of the distraction distance. The display 26 can provide afaster way to determine the distraction distance than visual inspectionof a scale. The display 26 can provide a more accurate way to determinethe distraction distance than visual inspection of a scale. The display26 can be easier to use than a scale visual to the user. The data outputof the display 26 can be in real-time. The display 26 can be positionedwithin the surgical field. The display 26 can be positioned to bevisible to the user during the procedure.

The display 26 can provide a visual reference to key anatomicalfeatures. The display 26 can provide a visual reference to Whiteside'sLine. The display 26 can provide a visual reference to Epicondyle axis.The display 26 can provide a visual reference to the mechanical axis.

The system 310, 510 can provide a balanced, rectangular flexion gap. Thesystem 310, 510 can provide an improvement in the ability to measure abalanced flexion gap. The system 310, 510 can provide an improvement inthe ability to achieve a balanced flexion gap. The system 310, 510 canprovide a guide to rotationally align the femoral component. The system310, 510 can provide an improvement in recording measurements during aprocedure. The system 310, 510 can provide an improvement in storingmeasurements during a procedure.

In some methods of use, the procedure can include one or more of thefollowing steps. The user can complete distal femoral resection. Thedistal femoral resection can be perpendicular to mechanical axis offemur in the coronal plane. The user can use the femoral preparationsystem 10 described herein. The user can complete tibial resection. Thetibial resection can be perpendicular to mechanical axis of femur in thecoronal plane. The user can use the tibial preparation system 210described herein. The user can insert the system 310, 510 between thetibia and femur. The user can distract the knee in full extension.

The system 310, 510 can include the surgical orientation device 14 andthe reference sensor device 16 described herein. In some embodiments,the system 310, 510 can use gyro propagation to measure coronal planeangle between tibial and femoral resections. The user can mount thesurgical orientation device 14 on femur rigid body. For instance, theuser can mount the surgical orientation device 14 on the second coupler374, 574. The reference sensor device 16 is at a fixed angle relative tothe surgical orientation device 14. For instance, the user can mount thereference sensor device 16 on the third coupler 378. The surgicalorientation device 14 and the reference sensor device 16 can be zeroed.The gyroscopes within the surgical orientation device 14 and thereference sensor device 16 can be zeroed. The reference sensor device 16can be moved to the tibia rigid body. For instance, the user can mountthe reference sensor device 16 on the first coupler 324, 524. The usercan read the tibio-femoral angle on the display 24 of the surgicalorientation device 14.

The user can release ligaments as needed to achieve target angle. Insome methods, the target angle is zero. The user can record thedistraction distance (extension gap). The user can remove the system310, 510 from the leg in extension.

The user can flex the knee 90°. The user can insert the system 310, 510between the tibia and femur. The user can apply distraction in flexion.The user can read the flexion gap on the display 24 of the surgicalorientation device 14. The user can read the flexion gap visually fromthe markings 340, 540. The user can calculate the anterior-posteriorshift needed to match flexion and extension gaps.

In some methods of use, the user can mount the drill guide 380 and drillholes with the appropriate AP shift from the preceding step. In somemethods of use, the user can measure posterior condyle angle on surgicalorientation device 14 from accelerometer measurements. The user can setimplant sizing/drill guide to this angle. In some methods of use, theuser either mounts the drill guide 380 and drill holes with theappropriate AP shift from preceding step or measures posterior condyleangle on surgical orientation device 14 from accelerometer measurementsand sets implant sizing/drill guide to this angle. In some embodiments,no soft tissue releases are need in flexion because 4-in-1 cutting block394 will be located with posterior resection slot parallel to tibialresection by correct alignment of drilled guide holes. The method caninclude mounting the implant sizing/drill guide on distal resectionsurface. The method can include drilling holes if not previouslycompleted. The user can read implant size and choose appropriate 4-in-1cutting block. The user can remove sizing/drill guide. The user canattach cutting block, locating using drilled holes. The user cancomplete resections.

In some methods of use, the user can mount the resection guide 580 andcut the femur with the appropriate AP shift from the preceding step. Insome methods of use, the user can measure posterior condyle angle onsurgical orientation device 14 prior the posterior cut. In someembodiments, the posterior condyle angle is measured only in flexion.The user can set implant sizing/drill guide to this angle. In somemethods, the user makes the posterior cut. In some methods, the usermakes one or more additional cuts based on the posterior cut. In somemethods, the user makes one or more additional cuts based onspecification from the implant manufacturer. In some methods, the usermakes one or more additional cuts based a cutting guide provided by themanufacturer. In some embodiments, soft tissue is released in extensionto balance the extension gap. In some embodiments, soft tissue is notreleased in flexion.

While the systems and methods presented herein are described in thecontext of a knee joint replacement procedure, the systems and/or theircomponents and methods can similarly be used in other types of medicalprocedures, including but not limited to shoulder and hip replacementprocedures.

Additionally, while the systems and methods presented herein aredescribed in the context of individual components and assemblies, insome embodiments one or more of the assemblies can be provided in theform of a kit for use by a surgeon. For example, in some embodiments akit can comprise each of the components of the femoral preparationsystem 10 and the tibial preparation system 210 described above. In someembodiments, a kit may comprise only the surgical orientation device 14and reference sensor device 16. In some embodiments a kit may compriseonly the femoral preparation system 10, or only the tibial preparationsystem 210. In some embodiments a kit may comprise only the system 310,510. Various other combinations and kits are also possible.

Although these inventions have been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present inventions extend beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the inventions and obvious modifications and equivalentsthereof. In addition, while several variations of the inventions havebeen shown and described in detail, other modifications, which arewithin the scope of these inventions, will be readily apparent to thoseof skill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments can be made and still fall within thescope of the inventions. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thedisclosed inventions. Thus, it is intended that the scope of at leastsome of the present inventions herein disclosed should not be limited bythe particular disclosed embodiments described above.

What is claimed is:
 1. A method of performing an orthopedic procedure,comprising: providing an orthopedic system comprising: a tibial memberconfigured to contact a tibia, wherein the tibial member comprises afirst coupler; a femoral member configured to contact a femur, whereinthe femoral member comprises a second coupler; an adjustment devicecoupling the tibial member and the femoral member; a first orientationdevice comprising a first inertial sensor and a user interfacecomprising a display screen; and a second orientation device comprisinga second inertial sensor, wherein the first orientation device and thesecond orientation device are releasably coupleable to the first couplerand the second coupler; coupling a first orientation device with one ofthe first coupler of the tibial member or the second coupler of thefemoral member; coupling a second orientation device with one of thefirst coupler of the tibial member or the second coupler of the femoralmember; collecting an inertial sensor output from the first inertialsensor or the second inertial sensor; and distracting the knee joint. 2.The method of claim 1, further comprising determining with the firstorientation device and the second orientation device a location of themechanical axis of a bone adjacent to the knee joint.
 3. The method ofclaim 1, further comprising displaying on the display screen theinertial sensor output from the first inertial sensor or the secondinertial sensor.
 4. The method of claim 1, further comprising storingthe inertial sensor output from the first inertial sensor or the secondinertial sensor.
 5. The method of claim 1, further comprising comparingthe inertial sensor output at a first time and a second time during theprocedure.
 6. The method of claim 1, further comprising collecting adistraction distance.
 7. The method of claim 6, wherein collecting thedistraction distance comprises capturing an image.
 8. A method ofperforming an orthopedic procedure, comprising: providing an orthopedicsystem comprising: a tibial member configured to contact a tibia,wherein the tibial member comprises a first coupler; a femoral memberconfigured to contact a femur, wherein the femoral member comprises asecond coupler; an adjustment device coupling the tibial member and thefemoral member; a first orientation device comprising a first inertialsensor and a user interface comprising a display screen; and a secondorientation device comprising a second inertial sensor, wherein thefirst orientation device and the second orientation device areconfigured to couple to and decouple from the first coupler and thesecond coupler; coupling the first orientation device with at least oneof the tibial member and the femoral member; coupling the secondorientation device with at least one of the tibial member and thefemoral member; inserting the tibial member and the femoral member inthe joint space; distracting the knee joint; and balancing the softtissue.
 9. The method of claim 8, further comprising displaying adistraction distance on the display screen of the first orientationdevice.
 10. The method of claim 8, further comprising displaying afemoral angle on the display screen of the first orientation device. 11.The method of claim 8, further comprising comparing a distractiondistance in extension and flexion.
 12. The method of claim 8, whereindistracting the knee joint comprises distracting the knee joint inextension.
 13. The method of claim 12, further comprising recording anextension gap distance.
 14. The method of claim 12, further comprisingdistracting the knee joint in flexion after recording an extension gapdistance.
 15. The method of claim 14, further comprising performing aposterior femoral cut corresponding to the extension gap measurement.16. The method of claim 8, wherein distracting the knee joint comprisesdistracting the knee joint in extension and balancing the soft tissuecomprises balancing the soft tissue in extension.
 17. The method ofclaim 8, wherein balancing the soft tissue comprises balancing the softtissue only in extension.
 18. The method of claim 8, further comprisingmeasuring a femoral rotation angle in extension and flexion.
 19. Themethod of claim 8, further comprising recording a femoral rotation anglein flexion.
 20. A method of performing an orthopedic procedure,comprising: coupling a first orientation device with at least one of atibial member and a femoral member, the first orientation devicecomprising a first inertial sensor; coupling a second orientation devicewith at least one of the tibial member and the femoral member; insertingthe tibial member and the femoral member in the joint space; distractingthe knee joint, wherein distracting the knee joint comprises distractingthe knee joint in extension; distracting the knee joint in flexion afterrecording an extension gap distance; matching the extension gap distancewith a marking on a resection guide; and balancing the soft tissue.